Revert "Revert "Speed up All Apps -> Workspace transition""

- also, undo enabling hardware layers for
    scroll indicator, which could have caused
    slowness
- fix bug where scroll indicator was not seen
    after the first visit to all apps
- eliminate a some needless hardware layer redraws
- making items under All Apps invisible when we're
    in All Apps
- making workspace spaces invisible if their alpha is 0
    to prevent more hardware layer rebuilding

This reverts commit 9753d13c7b.

Change-Id: Ib908ae0b456b2d4b8a171991a95f20aea4749da1

src/com/android/launcher2/SearchDropTargetBar.java

@@ -129,14 +129,26 @@ public class SearchDropTargetBar extends FrameLayout implements DragController.D
             @Override
             public void onAnimationStart(Animator animation) {
                 mQSBSearchBar.setVisibility(View.VISIBLE);
+                mQSBSearchBar.setLayerType(View.LAYER_TYPE_HARDWARE, null);
+            }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mQSBSearchBar.setLayerType(View.LAYER_TYPE_NONE, null);
             }
         });
         mQSBSearchBarFadeOutAnim = ObjectAnimator.ofFloat(mQSBSearchBar, "alpha", 0f);
         mQSBSearchBarFadeOutAnim.setDuration(sTransitionOutDuration);
         mQSBSearchBarFadeOutAnim.addListener(new AnimatorListenerAdapter() {
+            @Override
+            public void onAnimationStart(Animator animation) {
+                mQSBSearchBar.setLayerType(View.LAYER_TYPE_HARDWARE, null);
+            }
+
             @Override
             public void onAnimationEnd(Animator animation) {
                 mQSBSearchBar.setVisibility(View.INVISIBLE);
+                mQSBSearchBar.setLayerType(View.LAYER_TYPE_NONE, null);
             }
         });
     }