Experimental app list: "All apps" button has a folder-like icon.

ui/app_list/app_list_folder_item.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_APP_LIST_FOLDER_ITEM_H_
 #define UI_APP_LIST_APP_LIST_FOLDER_ITEM_H_
 
 #include <string>
 #include <vector>
 
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/app_list_item.h"
 #include "ui/app_list/app_list_item_list_observer.h"
 #include "ui/app_list/app_list_item_observer.h"
+#include "ui/app_list/folder_image.h"
 
 namespace gfx {
+class ImageSkia;
 class Rect;
 }
 
 namespace app_list {
 
 class AppListItemList;
 
 // AppListFolderItem implements the model/controller for folders.
 class APP_LIST_EXPORT AppListFolderItem : public AppListItem,
-                                          public AppListItemListObserver,
-                                          public AppListItemObserver {
+                                          public FolderImageObserver {
  public:
   // The folder type affects folder behavior.
   enum FolderType {
     // Default folder type.
     FOLDER_TYPE_NORMAL,
     // Items can not be moved to/from OEM folders in the UI.
     FOLDER_TYPE_OEM
   };
 
   static const char kItemType[];
 
   AppListFolderItem(const std::string& id, FolderType folder_type);
   ~AppListFolderItem() override;
 
-  // Updates the folder's icon.
-  void UpdateIcon();
-
   // Returns the icon of one of the top items with |item_index|.
   const gfx::ImageSkia& GetTopIcon(size_t item_index);
 
   // Returns the target icon bounds for |item| to fly back to its parent folder
   // icon in animation UI. If |item| is one of the top item icon, this will
   // match its corresponding top item icon in the folder icon. Otherwise,
   // the target icon bounds is centered at the |folder_icon_bounds| with
   // the same size of the top item icon.
   // The Rect returned is in the same coordinates of |folder_icon_bounds|.
   gfx::Rect GetTargetIconRectInFolderForItem(
       AppListItem* item, const gfx::Rect& folder_icon_bounds);
 
   AppListItemList* item_list() { return item_list_.get(); }
   const AppListItemList* item_list() const { return item_list_.get(); }
 
+  // For tests.
+  // TODO(mgiuca): return a const FolderImage& (requires that
+  // base::ObserverList::HasObserver takes a const*).

[Matt Giuca, 2014/10/29 07:14:51]

Note: I have a separate CL to do this. (Unless you can think of any reason why
base::ObserverList::HasObserver should require a non-const argument.)

[calamity, 2014/11/03 00:37:45]

Ack.

+  FolderImage* folder_image() { return &folder_image_; }
+
   FolderType folder_type() const { return folder_type_; }
 
   // AppListItem
   void Activate(int event_flags) override;
   const char* GetItemType() const override;
   ui::MenuModel* GetContextMenuModel() override;
   AppListItem* FindChildItem(const std::string& id) override;
   size_t ChildItemCount() const override;
   void OnExtensionPreferenceChanged() override;
   bool CompareForTest(const AppListItem* other) const override;
 
   // Returns an id for a new folder.
   static std::string GenerateId();
 
+  // FolderImageObserver overrides:
+  void OnFolderImageUpdated() override;
+
  private:
-  // AppListItemObserver
-  void ItemIconChanged() override;
-
-  // AppListItemListObserver
-  void OnListItemAdded(size_t index, AppListItem* item) override;
-  void OnListItemRemoved(size_t index, AppListItem* item) override;
-  ;
-  void OnListItemMoved(size_t from_index,
-                       size_t to_index,
-                       AppListItem* item) override;
-
-  void UpdateTopItems();
-
   // The type of folder; may affect behavior of folder views.
   const FolderType folder_type_;
 
   // List of items in the folder.
   scoped_ptr<AppListItemList> item_list_;
 
-  // Top items for generating folder icon.
-  std::vector<AppListItem*> top_items_;
+  FolderImage folder_image_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListFolderItem);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_FOLDER_ITEM_H_