Implement app list folder management page UI.

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 4c2c6fef6a10c7fcc4b1765f3d676625814f2948..1f3f938dbc37589b27834043ad995fe9e2709df6 100644
--- a/ui/app_list/views/contents_view.h
+++ b/ui/app_list/views/contents_view.h
@@ -23,9 +23,11 @@ namespace app_list {
 
 class AppsGridView;
 class ApplicationDragAndDropHost;
+class AppListFolderItem;
 class AppListMainView;
 class AppListModel;
 class AppListViewDelegate;
+class AppsContainerView;
 class PaginationModel;
 
 // A view to manage sub views under the search box (apps grid view + page
@@ -49,9 +51,12 @@ class ContentsView : public views::View {
       ApplicationDragAndDropHost* drag_and_drop_host);
 
   void ShowSearchResults(bool show);
+  void ShowFolderContent(AppListFolderItem* folder);
 
   void Prerender();
 
+  AppsContainerView* apps_container_view() { return apps_container_view_; }
+
  private:
   enum ShowState {
     SHOW_APPS,
@@ -80,7 +85,7 @@ class ContentsView : public views::View {
   ShowState show_state_;
   PaginationModel* pagination_model_;  // Owned by AppListController.
 
-  AppsGridView* apps_grid_view_;  // Owned by the view.
+  AppsContainerView* apps_container_view_; // Owned by the views hierarchy.
 
   scoped_ptr<views::ViewModel> view_model_;
   scoped_ptr<views::BoundsAnimator> bounds_animator_;