Remove over aggressive optimization.

It turns out that sometimes the wallpaper target is migrated to the
bottom of the window stack and then mWallpaperTarget is set to null.
In particular this happens when the launcher all-apps screen is
brought up. When this happens the layer of the wallpaper is
correctly set below the previous wallpaper target.

An optimization in WindowAnimator was keeping the layer update from
propagating to the Surface object. This fix removes that optimization.

Fixes bug 6631717.

Change-Id: I800dd043ce8df83b4e5edbf710503135396bc01e

Author: Craig Mautner

services/java/com/android/server/wm/WindowAnimator.java

@@ -496,15 +496,7 @@ synchronized void animate() {
 
             final int N = mWinAnimators.size();
             for (int i = 0; i < N; i++) {
-                final WindowStateAnimator winAnimator = mWinAnimators.get(i);
-                if (winAnimator.mWin.mIsWallpaper && mService.mWallpaperTarget == null) {
-                    if (!winAnimator.mWin.mWallpaperVisible && !winAnimator.mLastHidden) {
-                        // Wallpaper is no longer visible and there is no wp target => hide it.
-                        winAnimator.hide();
-                    }
-                    continue;
-                }
-                winAnimator.prepareSurfaceLocked(true);
+                mWinAnimators.get(i).prepareSurfaceLocked(true);
             }
 
             if (mDimParams != null) {

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

@@ -1063,7 +1063,10 @@ public void prepareSurfaceLocked(final boolean recoveringMemory) {
 
         setSurfaceBoundaries(recoveringMemory);
 
-        if (w.mAttachedHidden || !w.isReadyForDisplay()) {
+        if (mWin.mIsWallpaper && !mWin.mWallpaperVisible) {
+            // Wallpaper is no longer visible and there is no wp target => hide it.
+            hide();
+        } else if (w.mAttachedHidden || !w.isReadyForDisplay()) {
             hide();
             mAnimator.hideWallpapersLocked(w);