Notify launcher page with onTransitionChanged event

ui/app_list/views/contents_view.h

Index: ui/app_list/views/contents_view.h
diff --git a/ui/app_list/views/contents_view.h b/ui/app_list/views/contents_view.h
index ade7fdbf388fe4283e79e5a78e7a565b49903b8e..50adb7ba26668ca108f40d75290bde5545587db9 100644
--- a/ui/app_list/views/contents_view.h
+++ b/ui/app_list/views/contents_view.h
@@ -49,7 +49,7 @@ class APP_LIST_EXPORT ContentsView : public views::View,
   // Initialize the pages of the launcher. In the experimental launcher, should
   // be called after set_contents_switcher_view(), or switcher buttons will not
   // be created.
-  void Init(AppListModel* model, AppListViewDelegate* view_delegate);
+  void Init(AppListModel* model);
 
   // The app list gets closed and drag and drop operations need to be cancelled.
   void CancelDrag();
@@ -131,6 +131,12 @@ class APP_LIST_EXPORT ContentsView : public views::View,
   // with index |page_index|.
   gfx::Rect GetOffscreenPageBounds(int page_index) const;
 
+  // Notifies the view delegate that the custom launcher page's animation has
+  // changed.
+  void NotifyCustomLauncherPageAnimationChanged(double progress,
+                                                int current_page,
+                                                int target_page);
+
   // Calculates and sets the bounds for the subviews. If there is currently an
   // animation, this positions the views as appropriate for the current frame.
   void UpdatePageBounds();