Update wallpaper visibility at time of hide/show.

Call the Window client method dispatchAppVisibility when hiding or
showing wallpaper rather than wait until the next call to
performLayoutAndPlaceSurfaces.

Fixes bug 6645473.

Change-Id: I363f69f8db0affff92308e11ce52546401959d8f
diff --git a/services/java/com/android/server/wm/WindowStateAnimator.java b/services/java/com/android/server/wm/WindowStateAnimator.java
index bdacb6e..579cbb7 100644
--- a/services/java/com/android/server/wm/WindowStateAnimator.java
+++ b/services/java/com/android/server/wm/WindowStateAnimator.java
@@ -1122,6 +1122,9 @@
                                 + " during relayout");
                         if (showSurfaceRobustlyLocked()) {
                             mLastHidden = false;
+                            if (w.mIsWallpaper) {
+                                mService.dispatchWallpaperVisibility(w, true);
+                            }
                         } else {
                             w.mOrientationChanging = false;
                         }