Call onLauncherTransitionPrepare() and End() from pinch.

This makes the pinch transition more consistent with other transitions.
One immediate benefit of this is that it updates adjacent overview
panels during pinch, regardless of whether they are completely visible.

Previously the adjacent panels' alphas weren't always reset to 0.
Specifically, if you made a small pinch from workspace, which
canceled and went back to workspace, adjacent pages retained a
slightly visible panel.

Bug: 27676309
Change-Id: I7e79fddec31cd649e0811e4524b9a9a501c627f9

src/com/android/launcher3/allapps/AllAppsContainerView.java

@@ -514,7 +514,8 @@ public class AllAppsContainerView extends BaseContainerView implements DragSourc
     }
 
     @Override
-    public void onLauncherTransitionPrepare(Launcher l, boolean animated, boolean toWorkspace) {
+    public void onLauncherTransitionPrepare(Launcher l, boolean animated,
+            boolean multiplePagesVisible) {
         // Do nothing
     }