Implement transition for docking task in recents #1

- When the docking transition is happening, defer updating
the bounds of the home stack until the transition is done.
This is to preserve the scrim which is drawn in the recents
activity.
- Use the PROLONG_AT_START infrastructure to hide the task
in recents when starting the app transition.
- When recents finally get resized at the end of the transition,
reset it's draw state so we don't move the old surface around,
and the new surface gets drawn at the new position, to avoid
flickering.
- Remove hack around not layouting docked divider if it's not
visible, it's not needed anymore and resulted in a wrong
initial position.
- Fix animation selection for docked stack divider.
- Make sure win.moved() always gets called.

Bug: 27607141
Change-Id: I76c35f09461f044a90e2c88335008284b5839cc0
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 5cb04c8..ee406da 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -258,6 +258,12 @@
     // Current bounds of the stack or null if fullscreen.
     Rect mBounds = null;
 
+    boolean mUpdateBoundsDeferred;
+    boolean mUpdateBoundsDeferredCalled;
+    final Rect mDeferredBounds = new Rect();
+    final Rect mDeferredTaskBounds = new Rect();
+    final Rect mDeferredTaskInsetBounds = new Rect();
+
     long mLaunchStartTime = 0;
     long mFullyDrawnStartTime = 0;
 
@@ -427,6 +433,57 @@
         mActivityContainer.mActivityDisplay.mDisplay.getSize(out);
     }
 
+    /**
+     * Defers updating the bounds of the stack. If the stack was resized/repositioned while
+     * deferring, the bounds will update in {@link #continueUpdateBounds()}.
+     */
+    void deferUpdateBounds() {
+        if (!mUpdateBoundsDeferred) {
+            mUpdateBoundsDeferred = true;
+            mUpdateBoundsDeferredCalled = false;
+        }
+    }
+
+    /**
+     * Continues updating bounds after updates have been deferred. If there was a resize attempt
+     * between {@link #deferUpdateBounds()} and {@link #continueUpdateBounds()}, the stack will
+     * be resized to that bounds.
+     */
+    void continueUpdateBounds() {
+        final boolean wasDeferred = mUpdateBoundsDeferred;
+        mUpdateBoundsDeferred = false;
+        if (wasDeferred && mUpdateBoundsDeferredCalled) {
+            mStackSupervisor.resizeStackUncheckedLocked(this,
+                    mDeferredBounds.isEmpty() ? null : mDeferredBounds,
+                    mDeferredTaskBounds.isEmpty() ? null : mDeferredTaskBounds,
+                    mDeferredTaskInsetBounds.isEmpty() ? null : mDeferredTaskInsetBounds);
+        }
+    }
+
+    boolean updateBoundsAllowed(Rect bounds, Rect tempTaskBounds,
+            Rect tempTaskInsetBounds) {
+        if (!mUpdateBoundsDeferred) {
+            return true;
+        }
+        if (bounds != null) {
+            mDeferredBounds.set(bounds);
+        } else {
+            mDeferredBounds.setEmpty();
+        }
+        if (tempTaskBounds != null) {
+            mDeferredTaskBounds.set(tempTaskBounds);
+        } else {
+            mDeferredTaskBounds.setEmpty();
+        }
+        if (tempTaskInsetBounds != null) {
+            mDeferredTaskInsetBounds.set(tempTaskInsetBounds);
+        } else {
+            mDeferredTaskInsetBounds.setEmpty();
+        }
+        mUpdateBoundsDeferredCalled = true;
+        return false;
+    }
+
     void setBounds(Rect bounds) {
         mBounds = mFullscreen ? null : new Rect(bounds);
         if (mTaskPositioner != null) {