Notify launcher page with onTransitionChanged event

ui/app_list/views/app_list_main_view.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_APP_LIST_VIEWS_APP_LIST_MAIN_VIEW_H_
 #define UI_APP_LIST_VIEWS_APP_LIST_MAIN_VIEW_H_
 
 #include <string>
 
 #include "base/memory/scoped_vector.h"
@@ skipping 20 matching lines @@
 class PaginationModel;
 class SearchBoxView;
 
 // AppListMainView contains the normal view of the app list, which is shown
 // when the user is signed in.
 class APP_LIST_EXPORT AppListMainView : public views::View,
                                         public AppsGridViewDelegate,
                                         public SearchBoxViewDelegate,
                                         public SearchResultListViewDelegate {
  public:
-  // Takes ownership of |delegate|.
   explicit AppListMainView(AppListViewDelegate* delegate);
   ~AppListMainView() override;
 
   void Init(gfx::NativeView parent,
             int initial_apps_page,
             SearchBoxView* search_box_view);
 
   void ShowAppListWhenReady();
 
   void ResetForShow();
@@ skipping 13 matching lines @@
   // If |drag_and_drop_host| is not NULL it will be called upon drag and drop
   // operations outside the application list.
   void SetDragAndDropHostOfCurrentAppList(
       ApplicationDragAndDropHost* drag_and_drop_host);
 
   ContentsView* contents_view() const { return contents_view_; }
   ContentsSwitcherView* contents_switcher_view() const {
     return contents_switcher_view_;
   }
   AppListModel* model() { return model_; }
+  AppListViewDelegate* view_delegate() { return delegate_; }
 
   // Returns true if the app list should be centered and in landscape mode.
   bool ShouldCenterWindow() const;
 
   // Called when the search box's visibility is changed.
   void NotifySearchBoxVisibilityChanged();
 
  private:
   class IconLoader;
 
@@ skipping 44 matching lines @@
   ScopedVector<IconLoader> pending_icon_loaders_;
 
   base::WeakPtrFactory<AppListMainView> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListMainView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_APP_LIST_MAIN_VIEW_H_