Make sure preserved surface is removed when it's no longer needed

Preserved surface might be used for format change as well as surface
size change outside a drag resizing. We currently remove the preserved
surface in prepareSurfaceLocked() after the window is shown, but
sometimes app gets stopped before any animation pass is run.

bug: 28546172
Change-Id: I7f883f4b5c6da4dce70f94173b368a912056d062

services/core/java/com/android/server/wm/AppWindowToken.java

@@ -329,11 +329,14 @@ class AppWindowToken extends WindowToken {
         final DisplayContentList displayList = new DisplayContentList();
         for (int i = allWindows.size() - 1; i >= 0; i--) {
             final WindowState win = allWindows.get(i);
-            if (!win.mDestroying) {
+
+            if (!(mAppStopped || win.mWindowRemovalAllowed)) {
                 continue;
             }
 
-            if (!(mAppStopped || win.mWindowRemovalAllowed)) {
+            win.mWinAnimator.destroyPreservedSurfaceLocked();
+
+            if (!win.mDestroying) {
                 continue;
             }
 

services/core/java/com/android/server/wm/WindowStateAnimator.java

@@ -659,6 +659,13 @@ class WindowStateAnimator {
         mDestroyPreservedSurfaceUponRedraw = false;
     }
 
+    void markPreservedSurfaceForDestroy() {
+        if (mDestroyPreservedSurfaceUponRedraw
+                && !mService.mDestroyPreservedSurface.contains(mWin)) {
+            mService.mDestroyPreservedSurface.add(mWin);
+        }
+    }
+
     WindowSurfaceController createSurfaceLocked() {
         final WindowState w = mWin;
         if (w.hasSavedSurface()) {
@@ -1518,9 +1525,7 @@ class WindowStateAnimator {
 
             if (prepared && mLastHidden && mDrawState == HAS_DRAWN) {
                 if (showSurfaceRobustlyLocked()) {
-                    if (mDestroyPreservedSurfaceUponRedraw) {
+                    markPreservedSurfaceForDestroy();
-                        mService.mDestroyPreservedSurface.add(mWin);
-                    }
                     mAnimator.requestRemovalOfReplacedWindows(w);
                     mLastHidden = false;
                     if (mIsWallpaper) {