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/WindowAnimator.java b/services/java/com/android/server/wm/WindowAnimator.java
index efed0a4..894b523 100644
--- a/services/java/com/android/server/wm/WindowAnimator.java
+++ b/services/java/com/android/server/wm/WindowAnimator.java
@@ -93,6 +93,7 @@
                     final WindowStateAnimator winAnimator = wallpaper.mWinAnimator;
                     if (!winAnimator.mLastHidden) {
                         winAnimator.hide();
+                        mService.dispatchWallpaperVisibility(wallpaper, false);
                         mPendingLayoutChanges |= WindowManagerPolicy.FINISH_LAYOUT_REDO_WALLPAPER;
                     }
                 }