WindowState: Fix transaction usage in preserve surface

Currently we are using the global transaction without
opening it. Switch to the pending transaction.

Bug: 161937501
Test: Existing tests pass
Change-Id: Icf1215c278ce088d91bd7fb15f932f9ae6378d33

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

@@ -5009,9 +5009,10 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
             // on the new one. This prevents blinking when we change elevation of freeform and
             // pinned windows.
             if (!mWinAnimator.tryChangeFormatInPlaceLocked()) {
-                mWinAnimator.preserveSurfaceLocked();
+                mWinAnimator.preserveSurfaceLocked(getPendingTransaction());
                 result |= RELAYOUT_RES_SURFACE_CHANGED
                         | RELAYOUT_RES_FIRST_TIME;
+                scheduleAnimation();
             }
         }
 
@@ -5027,9 +5028,10 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
             // to preserve and destroy windows which are attached to another, they
             // will keep their surface and its size may change over time.
             if (mHasSurface && !isChildWindow()) {
-                mWinAnimator.preserveSurfaceLocked();
+                mWinAnimator.preserveSurfaceLocked(getPendingTransaction());
                 result |= RELAYOUT_RES_SURFACE_CHANGED |
                     RELAYOUT_RES_FIRST_TIME;
+                scheduleAnimation();
             }
         }
         final boolean freeformResizing = isDragResizing()

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

@@ -349,7 +349,7 @@ class WindowStateAnimator {
         return result;
     }
 
-    void preserveSurfaceLocked() {
+    void preserveSurfaceLocked(SurfaceControl.Transaction t) {
         if (mDestroyPreservedSurfaceUponRedraw) {
             // This could happen when switching the surface mode very fast. For example,
             // we preserved a surface when dragResizing changed to true. Then before the
@@ -376,7 +376,7 @@ class WindowStateAnimator {
             // Our SurfaceControl is always at layer 0 within the parent Surface managed by
             // window-state. We want this old Surface to stay on top of the new one
             // until we do the swap, so we place it at a positive layer.
-            mSurfaceController.mSurfaceControl.setLayer(PRESERVED_SURFACE_LAYER);
+            t.setLayer(mSurfaceController.getClientViewRootSurface(), PRESERVED_SURFACE_LAYER);
         }
         mDestroyPreservedSurfaceUponRedraw = true;
         mSurfaceDestroyDeferred = true;