Implement animation UI for opening/closing an app list folder.

ui/app_list/views/app_list_folder_view.h

Index: ui/app_list/views/app_list_folder_view.h
diff --git a/ui/app_list/views/app_list_folder_view.h b/ui/app_list/views/app_list_folder_view.h
index 85400696bfbf578baa3e846f1a8b200f7f33590d..ae721f712c1ec860b6e3a7828cec54856be2e306 100644
--- a/ui/app_list/views/app_list_folder_view.h
+++ b/ui/app_list/views/app_list_folder_view.h
@@ -7,6 +7,7 @@
 
 #include "ui/app_list/views/folder_header_view.h"
 #include "ui/app_list/views/folder_header_view_delegate.h"
+#include "ui/compositor/layer_animation_observer.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/view.h"
 
@@ -29,7 +30,8 @@ class FolderHeaderView;
 class PaginationModel;
 
 class AppListFolderView : public views::View,
-                          public FolderHeaderViewDelegate {
+                          public FolderHeaderViewDelegate,
+                          public ui::ImplicitAnimationObserver {
  public:
   AppListFolderView(AppsContainerView* container_view,
                     AppListModel* model,
@@ -39,11 +41,22 @@ class AppListFolderView : public views::View,
 
   void SetAppListFolderItem(AppListFolderItem* folder);
 
-  // Overridden from views::View:
+  // Schedules animation to show or hide the view.

[xiyuan, 2014/01/16 01:46:48]

nit: Schedules _an_ animation

[jennyz, 2014/01/16 17:49:52]

Done.

+  void ScheduleAnimationToShow(bool show);

[xiyuan, 2014/01/16 01:46:48]

nit: ScheduleAnimationToShow makes reader think it is runs animation for showing
the content but it is actually both ways and controlled by |show|. Can we get a
better name? Maybe ScheduleShowHideAnimation?

[jennyz, 2014/01/16 17:49:52]

Done.

+
+  // Gets icon image bounds of the item at |index|, relative to
+  // AppListFolderView.
+  gfx::Rect GetItemIconBoundsAt(int index);
+
+

[xiyuan, 2014/01/16 01:46:48]

nit: nuke one empty line

[jennyz, 2014/01/16 17:49:52]

Done.

+  // views::View overrides:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
 
+  // ui::ImplicitAnimationObserver overrides:
+  virtual void OnImplicitAnimationsCompleted() OVERRIDE;
+
  private:
   void CalculateIdealBounds();
 
@@ -61,6 +74,9 @@ class AppListFolderView : public views::View,
 
   scoped_ptr<PaginationModel> pagination_model_;
 
+  // Animated to show or hide the view.
+  bool animate_to_show_;
+
   DISALLOW_COPY_AND_ASSIGN(AppListFolderView);
 };