diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index d0e3fb4..d480fb7 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -91,8 +91,6 @@
         .PACKAGE;
 import static com.android.server.wm.ActivityStack.REMOVE_TASK_MODE_DESTROYING;
 import static com.android.server.wm.ActivityStackSupervisor.DEFER_RESUME;
-import static com.android.server.wm.ActivityStackSupervisor.MATCH_TASK_IN_STACKS_ONLY;
-import static com.android.server.wm.ActivityStackSupervisor.MATCH_TASK_IN_STACKS_OR_RECENT_TASKS;
 import static com.android.server.wm.ActivityStackSupervisor.ON_TOP;
 import static com.android.server.wm.ActivityStackSupervisor.PRESERVE_WINDOWS;
 import static com.android.server.wm.ActivityStackSupervisor.REMOVE_FROM_RECENTS;
@@ -122,6 +120,8 @@
 import static com.android.server.wm.ActivityTaskManagerService.UiHandler.DISMISS_DIALOG_UI_MSG;
 import static com.android.server.wm.RecentsAnimationController.REORDER_KEEP_IN_PLACE;
 import static com.android.server.wm.RecentsAnimationController.REORDER_MOVE_TO_ORIGINAL_POSITION;
+import static com.android.server.wm.RootActivityContainer.MATCH_TASK_IN_STACKS_ONLY;
+import static com.android.server.wm.RootActivityContainer.MATCH_TASK_IN_STACKS_OR_RECENT_TASKS;
 import static com.android.server.wm.TaskRecord.LOCK_TASK_AUTH_DONT_LOCK;
 import static com.android.server.wm.TaskRecord.REPARENT_KEEP_STACK_AT_FRONT;
 import static com.android.server.wm.TaskRecord.REPARENT_LEAVE_STACK_IN_PLACE;
@@ -352,6 +352,7 @@
     /* Global service lock used by the package the owns this service. */
     final WindowManagerGlobalLock mGlobalLock = new WindowManagerGlobalLock();
     ActivityStackSupervisor mStackSupervisor;
+    RootActivityContainer mRootActivityContainer;
     WindowManagerService mWindowManager;
     private UserManagerService mUserManager;
     private AppOpsService mAppOpsService;
@@ -766,7 +767,8 @@
         mTempConfig.setLocales(LocaleList.getDefault());
         mConfigurationSeq = mTempConfig.seq = 1;
         mStackSupervisor = createStackSupervisor();
-        mStackSupervisor.onConfigurationChanged(mTempConfig);
+        mRootActivityContainer = new RootActivityContainer(this);
+        mRootActivityContainer.onConfigurationChanged(mTempConfig);
 
         mTaskChangeNotificationController =
                 new TaskChangeNotificationController(mGlobalLock, mStackSupervisor, mH);
@@ -801,6 +803,7 @@
             mWindowManager = wm;
             mLockTaskController.setWindowManager(wm);
             mStackSupervisor.setWindowManager(wm);
+            mRootActivityContainer.setWindowManager(wm);
         }
     }
 
@@ -1255,7 +1258,7 @@
                 sourceToken = resultTo;
             }
 
-            sourceRecord = mStackSupervisor.isInAnyStackLocked(sourceToken);
+            sourceRecord = mRootActivityContainer.isInAnyStack(sourceToken);
             if (sourceRecord == null) {
                 throw new SecurityException("Called with bad activity token: " + sourceToken);
             }
@@ -1799,7 +1802,7 @@
                 }
                 final boolean translucentChanged = r.changeWindowTranslucency(true);
                 if (translucentChanged) {
-                    mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
+                    mRootActivityContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);
                 }
                 mWindowManager.setAppFullscreen(token, true);
                 return translucentChanged;
@@ -1829,7 +1832,7 @@
                 if (translucentChanged) {
                     r.getStack().convertActivityToTranslucent(r);
                 }
-                mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
+                mRootActivityContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);
                 mWindowManager.setAppFullscreen(token, false);
                 return translucentChanged;
             }
@@ -1842,7 +1845,7 @@
     public void notifyActivityDrawn(IBinder token) {
         if (DEBUG_VISIBILITY) Slog.d(TAG_VISIBILITY, "notifyActivityDrawn: token=" + token);
         synchronized (mGlobalLock) {
-            ActivityRecord r = mStackSupervisor.isInAnyStackLocked(token);
+            ActivityRecord r = mRootActivityContainer.isInAnyStack(token);
             if (r != null) {
                 r.getStack().notifyActivityDrawnLocked(r);
             }
@@ -1879,7 +1882,7 @@
             synchronized (mGlobalLock) {
                 ActivityStack focusedStack = getTopDisplayFocusedStack();
                 if (focusedStack != null) {
-                    return mStackSupervisor.getStackInfo(focusedStack.mStackId);
+                    return mRootActivityContainer.getStackInfo(focusedStack.mStackId);
                 }
                 return null;
             }
@@ -1895,14 +1898,14 @@
         final long callingId = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                final ActivityStack stack = mStackSupervisor.getStack(stackId);
+                final ActivityStack stack = mRootActivityContainer.getStack(stackId);
                 if (stack == null) {
                     Slog.w(TAG, "setFocusedStack: No stack with id=" + stackId);
                     return;
                 }
                 final ActivityRecord r = stack.topRunningActivityLocked();
                 if (r != null && r.moveFocusableActivityToTop("setFocusedStack")) {
-                    mStackSupervisor.resumeFocusedStacksTopActivitiesLocked();
+                    mRootActivityContainer.resumeFocusedStacksTopActivities();
                 }
             }
         } finally {
@@ -1917,14 +1920,14 @@
         final long callingId = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     return;
                 }
                 final ActivityRecord r = task.topRunningActivityLocked();
                 if (r != null && r.moveFocusableActivityToTop("setFocusedTask")) {
-                    mStackSupervisor.resumeFocusedStacksTopActivitiesLocked();
+                    mRootActivityContainer.resumeFocusedStacksTopActivities();
                 }
             }
         } finally {
@@ -2009,7 +2012,7 @@
             final long origId = Binder.clearCallingIdentity();
             try {
                 int taskId = ActivityRecord.getTaskForActivityLocked(token, !nonRoot);
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId);
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId);
                 if (task != null) {
                     return ActivityRecord.getStackLocked(token).moveTaskToBackLocked(taskId);
                 }
@@ -2027,7 +2030,7 @@
         Rect rect = new Rect();
         try {
             synchronized (mGlobalLock) {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_OR_RECENT_TASKS);
                 if (task == null) {
                     Slog.w(TAG, "getTaskBounds: taskId=" + taskId + " not found");
@@ -2058,7 +2061,7 @@
         synchronized (mGlobalLock) {
             enforceCallerIsRecentsOrHasPermission(
                     MANAGE_ACTIVITY_STACKS, "getTaskDescription()");
-            final TaskRecord tr = mStackSupervisor.anyTaskForIdLocked(id,
+            final TaskRecord tr = mRootActivityContainer.anyTaskForId(id,
                     MATCH_TASK_IN_STACKS_OR_RECENT_TASKS);
             if (tr != null) {
                 return tr.lastTaskDescription;
@@ -2078,7 +2081,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     Slog.w(TAG, "setTaskWindowingMode: No task for id=" + taskId);
@@ -2167,7 +2170,7 @@
         }
         final long origId = Binder.clearCallingIdentity();
         try {
-            final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId);
+            final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId);
             if (task == null) {
                 Slog.d(TAG, "Could not find task for id: "+ taskId);
                 SafeActivityOptions.abort(options);
@@ -2284,7 +2287,7 @@
 
             final boolean allowed = isGetTasksAllowed("getTasks", Binder.getCallingPid(),
                     callingUid);
-            mStackSupervisor.getRunningTasks(maxNum, list, ignoreActivityType,
+            mRootActivityContainer.getRunningTasks(maxNum, list, ignoreActivityType,
                     ignoreWindowingMode, callingUid, allowed);
         }
 
@@ -2320,7 +2323,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId);
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId);
                 if (task == null) {
                     Slog.w(TAG, "moveTaskToStack: No task for id=" + taskId);
                     return;
@@ -2329,7 +2332,7 @@
                 if (DEBUG_STACK) Slog.d(TAG_STACK, "moveTaskToStack: moving task=" + taskId
                         + " to stackId=" + stackId + " toTop=" + toTop);
 
-                final ActivityStack stack = mStackSupervisor.getStack(stackId);
+                final ActivityStack stack = mRootActivityContainer.getStack(stackId);
                 if (stack == null) {
                     throw new IllegalStateException(
                             "moveTaskToStack: No stack for stackId=" + stackId);
@@ -2359,7 +2362,7 @@
         try {
             synchronized (mGlobalLock) {
                 if (animate) {
-                    final PinnedActivityStack stack = mStackSupervisor.getStack(stackId);
+                    final PinnedActivityStack stack = mRootActivityContainer.getStack(stackId);
                     if (stack == null) {
                         Slog.w(TAG, "resizeStack: stackId " + stackId + " not found.");
                         return;
@@ -2371,12 +2374,12 @@
                     stack.animateResizePinnedStack(null /* sourceHintBounds */, destBounds,
                             animationDuration, false /* fromFullscreen */);
                 } else {
-                    final ActivityStack stack = mStackSupervisor.getStack(stackId);
+                    final ActivityStack stack = mRootActivityContainer.getStack(stackId);
                     if (stack == null) {
                         Slog.w(TAG, "resizeStack: stackId " + stackId + " not found.");
                         return;
                     }
-                    mStackSupervisor.resizeStackLocked(stack, destBounds,
+                    mRootActivityContainer.resizeStack(stack, destBounds,
                             null /* tempTaskBounds */, null /* tempTaskInsetBounds */,
                             preserveWindows, allowResizeInDockedMode, !DEFER_RESUME);
                 }
@@ -2410,7 +2413,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     Slog.w(TAG, "setTaskWindowingModeSplitScreenPrimary: No task for id=" + taskId);
@@ -2452,7 +2455,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                mStackSupervisor.removeStacksInWindowingModes(windowingModes);
+                mRootActivityContainer.removeStacksInWindowingModes(windowingModes);
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -2467,7 +2470,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                mStackSupervisor.removeStacksWithActivityTypes(activityTypes);
+                mRootActivityContainer.removeStacksWithActivityTypes(activityTypes);
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -2498,7 +2501,7 @@
         long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.getAllStackInfosLocked();
+                return mRootActivityContainer.getAllStackInfos();
             }
         } finally {
             Binder.restoreCallingIdentity(ident);
@@ -2511,7 +2514,7 @@
         long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.getStackInfo(windowingMode, activityType);
+                return mRootActivityContainer.getStackInfo(windowingMode, activityType);
             }
         } finally {
             Binder.restoreCallingIdentity(ident);
@@ -2553,7 +2556,7 @@
         long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     return;
@@ -2595,7 +2598,7 @@
             return;
         }
 
-        final ActivityStack stack = mStackSupervisor.getTopDisplayFocusedStack();
+        final ActivityStack stack = mRootActivityContainer.getTopDisplayFocusedStack();
         if (stack == null || task != stack.topTask()) {
             throw new IllegalArgumentException("Invalid task, not in foreground");
         }
@@ -2610,7 +2613,7 @@
         long ident = Binder.clearCallingIdentity();
         try {
             // When a task is locked, dismiss the pinned stack if it exists
-            mStackSupervisor.removeStacksInWindowingModes(WINDOWING_MODE_PINNED);
+            mRootActivityContainer.removeStacksInWindowingModes(WINDOWING_MODE_PINNED);
 
             getLockTaskController().startLockTaskMode(task, isSystemCaller, callingUid);
         } finally {
@@ -2712,7 +2715,7 @@
             try {
                 // TODO: VI Consider treating local voice interactions and voice tasks
                 // differently here
-                mStackSupervisor.finishVoiceTask(session);
+                mRootActivityContainer.finishVoiceTask(session);
             } finally {
                 Binder.restoreCallingIdentity(origId);
             }
@@ -2902,7 +2905,7 @@
     @Override
     public void setTaskResizeable(int taskId, int resizeableMode) {
         synchronized (mGlobalLock) {
-            final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(
+            final TaskRecord task = mRootActivityContainer.anyTaskForId(
                     taskId, MATCH_TASK_IN_STACKS_OR_RECENT_TASKS);
             if (task == null) {
                 Slog.w(TAG, "setTaskResizeable: taskId=" + taskId + " not found");
@@ -2918,7 +2921,7 @@
         long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     Slog.w(TAG, "resizeTask: taskId=" + taskId + " not found");
@@ -2983,7 +2986,7 @@
             final long origId = Binder.clearCallingIdentity();
             try {
                 final WindowProcessController app = getProcessController(appInt);
-                mStackSupervisor.releaseSomeActivitiesLocked(app, "low-mem");
+                mRootActivityContainer.releaseSomeActivitiesLocked(app, "low-mem");
             } finally {
                 Binder.restoreCallingIdentity(origId);
             }
@@ -3077,7 +3080,7 @@
         synchronized (mGlobalLock) {
             final long ident = Binder.clearCallingIdentity();
             try {
-                final ActivityStack stack = mStackSupervisor.getStack(stackId);
+                final ActivityStack stack = mRootActivityContainer.getStack(stackId);
                 if (stack == null) {
                     Slog.w(TAG, "removeStack: No stack with id=" + stackId);
                     return;
@@ -3102,7 +3105,7 @@
             try {
                 if (DEBUG_STACK) Slog.d(TAG_STACK, "moveStackToDisplay: moving stackId=" + stackId
                         + " to displayId=" + displayId);
-                mStackSupervisor.moveStackToDisplayLocked(stackId, displayId, ON_TOP);
+                mRootActivityContainer.moveStackToDisplay(stackId, displayId, ON_TOP);
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -3564,13 +3567,13 @@
             try {
                 if (DEBUG_STACK) Slog.d(TAG_STACK, "positionTaskInStack: positioning task="
                         + taskId + " in stackId=" + stackId + " at position=" + position);
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId);
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId);
                 if (task == null) {
                     throw new IllegalArgumentException("positionTaskInStack: no task for id="
                             + taskId);
                 }
 
-                final ActivityStack stack = mStackSupervisor.getStack(stackId);
+                final ActivityStack stack = mRootActivityContainer.getStack(stackId);
 
                 if (stack == null) {
                     throw new IllegalArgumentException("positionTaskInStack: no stack for id="
@@ -3625,7 +3628,7 @@
         try {
             synchronized (mGlobalLock) {
                 final ActivityStack stack =
-                        mStackSupervisor.getDefaultDisplay().getSplitScreenPrimaryStack();
+                        mRootActivityContainer.getDefaultDisplay().getSplitScreenPrimaryStack();
                 if (stack == null) {
                     Slog.w(TAG, "dismissSplitScreenMode: primary split-screen stack not found.");
                     return;
@@ -3635,7 +3638,7 @@
                     // Caller wants the current split-screen primary stack to be the top stack after
                     // it goes fullscreen, so move it to the front.
                     stack.moveToFront("dismissSplitScreenMode");
-                } else if (mStackSupervisor.isTopDisplayFocusedStack(stack)) {
+                } else if (mRootActivityContainer.isTopDisplayFocusedStack(stack)) {
                     // In this case the current split-screen primary stack shouldn't be the top
                     // stack after it goes fullscreen, but it current has focus, so we move the
                     // focus to the top-most split-screen secondary stack next to it.
@@ -3666,7 +3669,7 @@
         try {
             synchronized (mGlobalLock) {
                 final PinnedActivityStack stack =
-                        mStackSupervisor.getDefaultDisplay().getPinnedStack();
+                        mRootActivityContainer.getDefaultDisplay().getPinnedStack();
                 if (stack == null) {
                     Slog.w(TAG, "dismissPip: pinned stack not found.");
                     return;
@@ -3708,7 +3711,7 @@
         synchronized (mGlobalLock) {
             final long origId = Binder.clearCallingIdentity();
             try {
-                final ActivityStack stack = mStackSupervisor.getStack(fromStackId);
+                final ActivityStack stack = mRootActivityContainer.getStack(fromStackId);
                 if (stack != null){
                     if (!stack.isActivityTypeStandardOrUndefined()) {
                         throw new IllegalArgumentException(
@@ -3743,7 +3746,7 @@
 
             long ident = Binder.clearCallingIdentity();
             try {
-                return mStackSupervisor.moveTopStackActivityToPinnedStackLocked(stackId, bounds);
+                return mRootActivityContainer.moveTopStackActivityToPinnedStack(stackId);
             } finally {
                 Binder.restoreCallingIdentity(ident);
             }
@@ -3821,7 +3824,7 @@
                         // Adjust the source bounds by the insets for the transition down
                         final Rect sourceBounds = new Rect(
                                 r.pictureInPictureArgs.getSourceRectHint());
-                        mStackSupervisor.moveActivityToPinnedStackLocked(
+                        mRootActivityContainer.moveActivityToPinnedStack(
                                 r, sourceBounds, aspectRatio, "enterPictureInPictureMode");
                         final PinnedActivityStack stack = r.getStack();
                         stack.setPictureInPictureAspectRatio(aspectRatio);
@@ -4100,7 +4103,7 @@
 
         synchronized (mGlobalLock) {
             // Check if display is initialized in AM.
-            if (!mStackSupervisor.isDisplayAdded(displayId)) {
+            if (!mRootActivityContainer.isDisplayAdded(displayId)) {
                 // Call might come when display is not yet added or has already been removed.
                 if (DEBUG_CONFIGURATION) {
                     Slog.w(TAG, "Trying to update display configuration for non-existing displayId="
@@ -4190,7 +4193,7 @@
         final long ident = Binder.clearCallingIdentity();
         try {
             synchronized (mGlobalLock) {
-                final TaskRecord task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                final TaskRecord task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_ONLY);
                 if (task == null) {
                     Slog.w(TAG, "cancelTaskWindowTransition: taskId=" + taskId + " not found");
@@ -4210,7 +4213,7 @@
         try {
             final TaskRecord task;
             synchronized (mGlobalLock) {
-                task = mStackSupervisor.anyTaskForIdLocked(taskId,
+                task = mRootActivityContainer.anyTaskForId(taskId,
                         MATCH_TASK_IN_STACKS_OR_RECENT_TASKS);
                 if (task == null) {
                     Slog.w(TAG, "getTaskSnapshot: taskId=" + taskId + " not found");
@@ -4430,7 +4433,7 @@
         if (r.requestedVrComponent != null && r.getDisplayId() != DEFAULT_DISPLAY) {
             Slog.i(TAG, "Moving " + r.shortComponentName + " from stack " + r.getStackId()
                     + " to main stack for VR");
-            final ActivityStack stack = mStackSupervisor.getDefaultDisplay().getOrCreateStack(
+            final ActivityStack stack = mRootActivityContainer.getDefaultDisplay().getOrCreateStack(
                     WINDOWING_MODE_FULLSCREEN, r.getActivityType(), true /* toTop */);
             moveTaskToStack(r.getTask().taskId, stack.mStackId, true /* toTop */);
         }
@@ -4444,7 +4447,7 @@
                 if (disableNonVrUi) {
                     // If we are in a VR mode where Picture-in-Picture mode is unsupported,
                     // then remove the pinned stack.
-                    mStackSupervisor.removeStacksInWindowingModes(WINDOWING_MODE_PINNED);
+                    mRootActivityContainer.removeStacksInWindowingModes(WINDOWING_MODE_PINNED);
                 }
             }
         });
@@ -4496,7 +4499,7 @@
     }
 
     ActivityStack getTopDisplayFocusedStack() {
-        return mStackSupervisor.getTopDisplayFocusedStack();
+        return mRootActivityContainer.getTopDisplayFocusedStack();
     }
 
     /** Pokes the task persister. */
@@ -4557,12 +4560,12 @@
             int opti, boolean dumpAll, boolean dumpClient, String dumpPackage, String header) {
         pw.println(header);
 
-        boolean printedAnything = mStackSupervisor.dumpActivitiesLocked(fd, pw, dumpAll, dumpClient,
+        boolean printedAnything = mRootActivityContainer.dumpActivities(fd, pw, dumpAll, dumpClient,
                 dumpPackage);
         boolean needSep = printedAnything;
 
         boolean printed = ActivityStackSupervisor.printThisActivity(pw,
-                mStackSupervisor.getTopResumedActivity(),  dumpPackage, needSep,
+                mRootActivityContainer.getTopResumedActivity(),  dumpPackage, needSep,
                 "  ResumedActivity: ");
         if (printed) {
             printedAnything = true;
@@ -4584,7 +4587,7 @@
 
     void dumpActivityContainersLocked(PrintWriter pw) {
         pw.println("ACTIVITY MANAGER STARTER (dumpsys activity containers)");
-        mStackSupervisor.dumpChildrenNames(pw, " ");
+        mRootActivityContainer.dumpChildrenNames(pw, " ");
         pw.println(" ");
     }
 
@@ -4608,7 +4611,7 @@
         ArrayList<ActivityRecord> activities;
 
         synchronized (mGlobalLock) {
-            activities = mStackSupervisor.getDumpActivitiesLocked(name, dumpVisibleStacksOnly,
+            activities = mRootActivityContainer.getDumpActivities(name, dumpVisibleStacksOnly,
                     dumpFocusedStackOnly);
         }
 
@@ -4683,7 +4686,7 @@
     }
 
     void writeSleepStateToProto(ProtoOutputStream proto) {
-        for (ActivityTaskManagerInternal.SleepToken st : mStackSupervisor.mSleepTokens) {
+        for (ActivityTaskManagerInternal.SleepToken st : mRootActivityContainer.mSleepTokens) {
             proto.write(ActivityManagerServiceDumpProcessesProto.SleepStatus.SLEEP_TOKENS,
                     st.toString());
         }
@@ -4728,7 +4731,7 @@
      * also corresponds to the merged configuration of the default display.
      */
     Configuration getGlobalConfiguration() {
-        return mStackSupervisor.getConfiguration();
+        return mRootActivityContainer.getConfiguration();
     }
 
     boolean updateConfigurationLocked(Configuration values, ActivityRecord starting,
@@ -4860,7 +4863,7 @@
         mTempConfig.seq = increaseConfigurationSeqLocked();
 
         // Update stored global config and notify everyone about the change.
-        mStackSupervisor.onConfigurationChanged(mTempConfig);
+        mRootActivityContainer.onConfigurationChanged(mTempConfig);
 
         Slog.i(TAG, "Config changes=" + Integer.toHexString(changes) + " " + mTempConfig);
         // TODO(multi-display): Update UsageEvents#Event to include displayId.
@@ -4907,7 +4910,7 @@
 
         // Override configuration of the default display duplicates global config, so we need to
         // update it also. This will also notify WindowManager about changes.
-        performDisplayOverrideConfigUpdate(mStackSupervisor.getConfiguration(), deferResume,
+        performDisplayOverrideConfigUpdate(mRootActivityContainer.getConfiguration(), deferResume,
                 DEFAULT_DISPLAY);
 
         return changes;
@@ -4961,12 +4964,12 @@
 
     private int performDisplayOverrideConfigUpdate(Configuration values, boolean deferResume,
             int displayId) {
-        mTempConfig.setTo(mStackSupervisor.getDisplayOverrideConfiguration(displayId));
+        mTempConfig.setTo(mRootActivityContainer.getDisplayOverrideConfiguration(displayId));
         final int changes = mTempConfig.updateFrom(values);
         if (changes != 0) {
             Slog.i(TAG, "Override config changes=" + Integer.toHexString(changes) + " "
                     + mTempConfig + " for displayId=" + displayId);
-            mStackSupervisor.setDisplayOverrideConfiguration(mTempConfig, displayId);
+            mRootActivityContainer.setDisplayOverrideConfiguration(mTempConfig, displayId);
 
             final boolean isDensityChange = (changes & ActivityInfo.CONFIG_DENSITY) != 0;
             if (isDensityChange && displayId == DEFAULT_DISPLAY) {
@@ -5096,7 +5099,7 @@
                     mCurAppTimeTracker.stop();
                     mH.obtainMessage(
                             REPORT_TIME_TRACKER_MSG, mCurAppTimeTracker).sendToTarget();
-                    mStackSupervisor.clearOtherAppTimeTrackers(r.appTimeTracker);
+                    mRootActivityContainer.clearOtherAppTimeTrackers(r.appTimeTracker);
                     mCurAppTimeTracker = null;
                 }
                 if (r.appTimeTracker != null) {
@@ -5157,14 +5160,15 @@
 
     ActivityTaskManagerInternal.SleepToken acquireSleepToken(String tag, int displayId) {
         synchronized (mGlobalLock) {
-            final ActivityTaskManagerInternal.SleepToken token = mStackSupervisor.createSleepTokenLocked(tag, displayId);
+            final ActivityTaskManagerInternal.SleepToken token =
+                    mRootActivityContainer.createSleepToken(tag, displayId);
             updateSleepIfNeededLocked();
             return token;
         }
     }
 
     void updateSleepIfNeededLocked() {
-        final boolean shouldSleep = !mStackSupervisor.hasAwakeDisplay();
+        final boolean shouldSleep = !mRootActivityContainer.hasAwakeDisplay();
         final boolean wasSleeping = mSleeping;
         boolean updateOomAdj = false;
 
@@ -5180,7 +5184,7 @@
                 mTopProcessState = ActivityManager.PROCESS_STATE_TOP;
                 mStackSupervisor.comeOutOfSleepIfNeededLocked();
             }
-            mStackSupervisor.applySleepTokensLocked(true /* applyToStacks */);
+            mRootActivityContainer.applySleepTokens(true /* applyToStacks */);
             if (wasSleeping) {
                 updateOomAdj = true;
             }
@@ -5356,7 +5360,7 @@
 
     // TODO(b/111541062): Update app time tracking to make it aware of multiple resumed activities
     private void startTimeTrackingFocusedActivityLocked() {
-        final ActivityRecord resumedActivity = mStackSupervisor.getTopResumedActivity();
+        final ActivityRecord resumedActivity = mRootActivityContainer.getTopResumedActivity();
         if (!mSleeping && mCurAppTimeTracker != null && resumedActivity != null) {
             mCurAppTimeTracker.start(resumedActivity.packageName);
         }
@@ -5381,7 +5385,7 @@
     /** Applies latest configuration and/or visibility updates if needed. */
     private boolean ensureConfigAndVisibilityAfterUpdate(ActivityRecord starting, int changes) {
         boolean kept = true;
-        final ActivityStack mainStack = mStackSupervisor.getTopDisplayFocusedStack();
+        final ActivityStack mainStack = mRootActivityContainer.getTopDisplayFocusedStack();
         // mainStack is null during startup.
         if (mainStack != null) {
             if (changes != 0 && starting == null) {
@@ -5396,7 +5400,7 @@
                         false /* preserveWindow */);
                 // And we need to make sure at this point that all other activities
                 // are made visible with the correct configuration.
-                mStackSupervisor.ensureActivitiesVisibleLocked(starting, changes,
+                mRootActivityContainer.ensureActivitiesVisible(starting, changes,
                         !PRESERVE_WINDOWS);
             }
         }
@@ -5612,8 +5616,8 @@
         @Override
         public ComponentName getHomeActivityForUser(int userId) {
             synchronized (mGlobalLock) {
-                ActivityRecord homeActivity =
-                        mStackSupervisor.getDefaultDisplayHomeActivityForUser(userId);
+                final ActivityRecord homeActivity =
+                        mRootActivityContainer.getDefaultDisplayHomeActivityForUser(userId);
                 return homeActivity == null ? null : homeActivity.realActivity;
             }
         }
@@ -5651,14 +5655,14 @@
         @Override
         public List<IBinder> getTopVisibleActivities() {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.getTopVisibleActivities();
+                return mRootActivityContainer.getTopVisibleActivities();
             }
         }
 
         @Override
         public void notifyDockedStackMinimizedChanged(boolean minimized) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.setDockedStackMinimized(minimized);
+                mRootActivityContainer.setDockedStackMinimized(minimized);
             }
         }
 
@@ -5739,7 +5743,7 @@
                 // We might change the visibilities here, so prepare an empty app transition which
                 // might be overridden later if we actually change visibilities.
                 final ActivityDisplay activityDisplay =
-                        mStackSupervisor.getActivityDisplay(displayId);
+                        mRootActivityContainer.getActivityDisplay(displayId);
                 if (activityDisplay == null) {
                     return;
                 }
@@ -5748,7 +5752,7 @@
                 if (!wasTransitionSet) {
                     dwc.prepareAppTransition(TRANSIT_NONE, false /* alwaysKeepCurrent */);
                 }
-                mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
+                mRootActivityContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);
 
                 // If there was a transition set already we don't want to interfere with it as we
                 // might be starting it too early.
@@ -5765,7 +5769,7 @@
         public void notifyKeyguardTrustedChanged() {
             synchronized (mGlobalLock) {
                 if (mKeyguardController.isKeyguardShowing(DEFAULT_DISPLAY)) {
-                    mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
+                    mRootActivityContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);
                 }
             }
         }
@@ -5792,7 +5796,7 @@
                             "setFocusedActivity: No activity record matching token=" + token);
                 }
                 if (r.moveFocusableActivityToTop("setFocusedActivity")) {
-                    mStackSupervisor.resumeFocusedStacksTopActivitiesLocked();
+                    mRootActivityContainer.resumeFocusedStacksTopActivities();
                 }
             }
         }
@@ -5943,7 +5947,7 @@
         public boolean shuttingDown(boolean booted, int timeout) {
             synchronized (mGlobalLock) {
                 mShuttingDown = true;
-                mStackSupervisor.prepareForShutdownLocked();
+                mRootActivityContainer.prepareForShutdown();
                 updateEventDispatchingLocked(booted);
                 notifyTaskPersisterLocked(null, true);
                 return mStackSupervisor.shutdownLocked(timeout);
@@ -6050,7 +6054,7 @@
         @Override
         public void onPackageReplaced(ApplicationInfo aInfo) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.updateActivityApplicationInfoLocked(aInfo);
+                mRootActivityContainer.updateActivityApplicationInfo(aInfo);
             }
         }
 
@@ -6080,7 +6084,7 @@
             mH.post(() -> {
                 synchronized (mGlobalLock) {
                     final ActivityDisplay activityDisplay =
-                            mStackSupervisor.getActivityDisplay(displayId);
+                            mRootActivityContainer.getActivityDisplay(displayId);
                     if (activityDisplay == null) {
                         // Call might come when display is not yet added or has been removed.
                         if (DEBUG_CONFIGURATION) {
@@ -6163,14 +6167,14 @@
         @Override
         public boolean startHomeActivity(int userId, String reason) {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.startHomeOnDisplay(userId, reason, DEFAULT_DISPLAY);
+                return mRootActivityContainer.startHomeOnDisplay(userId, reason, DEFAULT_DISPLAY);
             }
         }
 
         @Override
         public boolean startHomeOnAllDisplays(int userId, String reason) {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.startHomeOnAllDisplays(userId, reason);
+                return mRootActivityContainer.startHomeOnAllDisplays(userId, reason);
             }
         }
 
@@ -6234,7 +6238,7 @@
                 Runnable finishInstrumentationCallback) {
             synchronized (mGlobalLock) {
                 // Remove this application's activities from active lists.
-                boolean hasVisibleActivities = mStackSupervisor.handleAppDiedLocked(wpc);
+                boolean hasVisibleActivities = mRootActivityContainer.handleAppDied(wpc);
 
                 wpc.clearRecentTasks();
                 wpc.clearActivities();
@@ -6246,12 +6250,12 @@
                 mWindowManager.deferSurfaceLayout();
                 try {
                     if (!restarting && hasVisibleActivities
-                            && !mStackSupervisor.resumeFocusedStacksTopActivitiesLocked()) {
+                            && !mRootActivityContainer.resumeFocusedStacksTopActivities()) {
                         // If there was nothing to resume, and we are not already restarting this
                         // process, but there is a visible activity that is hosted by the process...
                         // then make sure all visible activities are running, taking care of
                         // restarting this process.
-                        mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
+                        mRootActivityContainer.ensureActivitiesVisible(null, 0, !PRESERVE_WINDOWS);
                     }
                 } finally {
                     mWindowManager.continueSurfaceLayout();
@@ -6280,7 +6284,7 @@
                     }
                     mWindowManager.closeSystemDialogs(reason);
 
-                    mStackSupervisor.closeSystemDialogsLocked();
+                    mRootActivityContainer.closeSystemDialogs();
                 }
                 // Call into AM outside the synchronized block.
                 mAmInternal.broadcastCloseSystemDialogs(reason);
@@ -6294,9 +6298,9 @@
                 String packageName, Set<String> disabledClasses, int userId, boolean booted) {
             synchronized (mGlobalLock) {
                 // Clean-up disabled activities.
-                if (mStackSupervisor.finishDisabledPackageActivitiesLocked(
+                if (mRootActivityContainer.finishDisabledPackageActivities(
                         packageName, disabledClasses, true, false, userId) && booted) {
-                    mStackSupervisor.resumeFocusedStacksTopActivitiesLocked();
+                    mRootActivityContainer.resumeFocusedStacksTopActivities();
                     mStackSupervisor.scheduleIdleLocked();
                 }
 
@@ -6313,7 +6317,7 @@
 
                 boolean didSomething =
                         getActivityStartController().clearPendingActivityLaunches(packageName);
-                didSomething |= mStackSupervisor.finishDisabledPackageActivitiesLocked(packageName,
+                didSomething |= mRootActivityContainer.finishDisabledPackageActivities(packageName,
                         null, doit, evenPersistent, userId);
                 return didSomething;
             }
@@ -6322,7 +6326,7 @@
         @Override
         public void resumeTopActivities(boolean scheduleIdle) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.resumeFocusedStacksTopActivitiesLocked();
+                mRootActivityContainer.resumeFocusedStacksTopActivities();
                 if (scheduleIdle) {
                     mStackSupervisor.scheduleIdleLocked();
                 }
@@ -6339,7 +6343,7 @@
         @Override
         public boolean attachApplication(WindowProcessController wpc) throws RemoteException {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.attachApplicationLocked(wpc);
+                return mRootActivityContainer.attachApplication(wpc);
             }
         }
 
@@ -6361,7 +6365,7 @@
                             // Showing launcher to avoid user entering credential twice.
                             startHomeActivity(currentUserId, "notifyLockedProfile");
                         }
-                        mStackSupervisor.lockAllProfileTasks(userId);
+                        mRootActivityContainer.lockAllProfileTasks(userId);
                     }
                 } finally {
                     Binder.restoreCallingIdentity(ident);
@@ -6382,7 +6386,7 @@
                     ActivityOptions activityOptions = options != null
                             ? new ActivityOptions(options) : ActivityOptions.makeBasic();
                     final ActivityRecord homeActivity =
-                            mStackSupervisor.getDefaultDisplayHomeActivity();
+                            mRootActivityContainer.getDefaultDisplayHomeActivity();
                     if (homeActivity != null) {
                         activityOptions.setLaunchTaskId(homeActivity.getTask().taskId);
                     }
@@ -6399,7 +6403,7 @@
             synchronized (mGlobalLock) {
                 // The output proto of "activity --proto activities"
                 // is ActivityManagerServiceDumpActivitiesProto
-                mStackSupervisor.writeToProto(proto,
+                mRootActivityContainer.writeToProto(proto,
                         ActivityManagerServiceDumpActivitiesProto.ACTIVITY_STACK_SUPERVISOR);
             }
         }
@@ -6494,7 +6498,7 @@
                 }
                 if (dumpPackage == null) {
                     pw.println("  mGlobalConfiguration: " + getGlobalConfiguration());
-                    mStackSupervisor.dumpDisplayConfigs(pw, "  ");
+                    mRootActivityContainer.dumpDisplayConfigs(pw, "  ");
                 }
                 if (dumpAll) {
                     if (dumpPackage == null) {
@@ -6522,7 +6526,7 @@
                 if (dumpPackage == null) {
                     pw.println("  mWakefulness="
                             + PowerManagerInternal.wakefulnessToString(wakefulness));
-                    pw.println("  mSleepTokens=" + mStackSupervisor.mSleepTokens);
+                    pw.println("  mSleepTokens=" + mRootActivityContainer.mSleepTokens);
                     if (mRunningVoice != null) {
                         pw.println("  mRunningVoice=" + mRunningVoice);
                         pw.println("  mVoiceWakeLock" + mVoiceWakeLock);
@@ -6649,14 +6653,14 @@
         @Override
         public boolean canGcNow() {
             synchronized (mGlobalLock) {
-                return isSleeping() || mStackSupervisor.allResumedActivitiesIdle();
+                return isSleeping() || mRootActivityContainer.allResumedActivitiesIdle();
             }
         }
 
         @Override
         public WindowProcessController getTopApp() {
             synchronized (mGlobalLock) {
-                final ActivityRecord top = mStackSupervisor.getTopResumedActivity();
+                final ActivityRecord top = mRootActivityContainer.getTopResumedActivity();
                 return top != null ? top.app : null;
             }
         }
@@ -6664,8 +6668,8 @@
         @Override
         public void rankTaskLayersIfNeeded() {
             synchronized (mGlobalLock) {
-                if (mStackSupervisor != null) {
-                    mStackSupervisor.rankTaskLayersIfNeeded();
+                if (mRootActivityContainer != null) {
+                    mRootActivityContainer.rankTaskLayersIfNeeded();
                 }
             }
         }
@@ -6673,35 +6677,35 @@
         @Override
         public void scheduleDestroyAllActivities(String reason) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.scheduleDestroyAllActivities(null, reason);
+                mRootActivityContainer.scheduleDestroyAllActivities(null, reason);
             }
         }
 
         @Override
         public void removeUser(int userId) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.removeUserLocked(userId);
+                mRootActivityContainer.removeUser(userId);
             }
         }
 
         @Override
         public boolean switchUser(int userId, UserState userState) {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.switchUserLocked(userId, userState);
+                return mRootActivityContainer.switchUser(userId, userState);
             }
         }
 
         @Override
         public void onHandleAppCrash(WindowProcessController wpc) {
             synchronized (mGlobalLock) {
-                mStackSupervisor.handleAppCrashLocked(wpc);
+                mRootActivityContainer.handleAppCrash(wpc);
             }
         }
 
         @Override
         public int finishTopCrashedActivities(WindowProcessController crashedApp, String reason) {
             synchronized (mGlobalLock) {
-                return mStackSupervisor.finishTopCrashedActivitiesLocked(crashedApp, reason);
+                return mRootActivityContainer.finishTopCrashedActivities(crashedApp, reason);
             }
         }