Reland: Clear transitions for app windows display change.

This prevents unwanted animations from running for windows on the new
display that are no longer relevant.
Also,
- Transfer the opening app token transition to the new display so that
it can be eventually made visible on that display
- Clean-up TODO relating to moving VR activity to main display, so that
the right states are set.

Bug: 128449959
Test: VrDisplayTests
Test: manual - launch activity with options moving between virtual and
default display, atest WmTests

Change-Id: I285c6742839d38e76322621b9c2a1d7f313cd6f8
diff --git a/services/core/java/com/android/server/wm/AppWindowToken.java b/services/core/java/com/android/server/wm/AppWindowToken.java
index 4a9a3f7..03cae42 100644
--- a/services/core/java/com/android/server/wm/AppWindowToken.java
+++ b/services/core/java/com/android/server/wm/AppWindowToken.java
@@ -1322,7 +1322,15 @@
         if (prevDc == null || prevDc == mDisplayContent) {
             return;
         }
-        if (prevDc.mChangingApps.contains(this)) {
+
+        if (prevDc.mOpeningApps.remove(this)) {
+            // Transfer opening transition to new display.
+            mDisplayContent.mOpeningApps.add(this);
+            mDisplayContent.prepareAppTransition(prevDc.mAppTransition.getAppTransition(), true);
+            mDisplayContent.executeAppTransition();
+        }
+
+        if (prevDc.mChangingApps.remove(this)) {
             // This gets called *after* the AppWindowToken has been reparented to the new display.
             // That reparenting resulted in this window changing modes (eg. FREEFORM -> FULLSCREEN),
             // so this token is now "frozen" while waiting for the animation to start on prevDc
@@ -1331,6 +1339,8 @@
             // so we need to cancel the change transition here.
             clearChangeLeash(getPendingTransaction(), true /* cancel */);
         }
+        prevDc.mClosingApps.remove(this);
+
         if (prevDc.mFocusedApp == this) {
             prevDc.setFocusedApp(null);
             final TaskStack stack = dc.getTopStack();
@@ -3216,16 +3226,6 @@
                 true /* topToBottom */);
     }
 
-    void removeFromPendingTransition() {
-        if (isWaitingForTransitionStart() && mDisplayContent != null) {
-            mDisplayContent.mOpeningApps.remove(this);
-            if (mDisplayContent.mChangingApps.remove(this)) {
-                clearChangeLeash(getPendingTransaction(), true /* cancel */);
-            }
-            mDisplayContent.mClosingApps.remove(this);
-        }
-    }
-
     private void updateColorTransform() {
         if (mSurfaceControl != null && mLastAppSaturationInfo != null) {
             getPendingTransaction().setColorTransform(mSurfaceControl,