Cleanup some incorrect / noisey calls to CustomContentCallbacks#onShow / onHide

-> In some instances, onResume would incorrectly call onShow
-> When pressing Home from CustomContent, we'd get a sequence of onHide,
   onShow, and then onHide due to some deferred actions in onNewIntent.
   Got rid of the onShow.

issue 17629011

Change-Id: I9b4f2ef682f5a7060e68210866fa05452076e428

src/com/android/launcher3/Workspace.java

@@ -1606,7 +1606,7 @@ public class Workspace extends PagedView
     }
 
     public boolean isOnOrMovingToCustomContent() {
-        return hasCustomContent() && getNextPage() == 0;
+        return hasCustomContent() && getNextPage() == 0 && mRestorePage == INVALID_RESTORE_PAGE;
     }
 
     private void updateStateForCustomContent(int screenCenter) {