Revert "Revert onSurfaceRedrawNeeded behavior"

This reverts commit d51863e994.

Reason for revert: Caused b/116859106
Fixes: 116859106

Change-Id: I12de0aa8d71164da29e3d40b4e0bd847c70f680c

packages/SystemUI/src/com/android/systemui/ImageWallpaper.java

@@ -256,6 +256,12 @@ public class ImageWallpaper extends WallpaperService {
                 Log.d(TAG, "onSurfaceRedrawNeeded");
             }
             super.onSurfaceRedrawNeeded(holder);
+            // At the end of this method we should have drawn into the surface.
+            // This means that the bitmap should be loaded synchronously if
+            // it was already unloaded.
+            if (mBackground == null) {
+                updateBitmap(mWallpaperManager.getBitmap(true /* hardware */));
+            }
             mSurfaceRedrawNeeded = true;
             drawFrame();
         }