app_list: Improve initial icon loading.

ui/app_list/app_list_view.h

 // Copyright (c) 2012 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_VIEW_H_
 #define UI_APP_LIST_APP_LIST_VIEW_H_
 
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "base/timer.h"
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/apps_grid_view_delegate.h"
 #include "ui/app_list/search_box_view_delegate.h"
 #include "ui/app_list/search_result_list_view_delegate.h"
 #include "ui/views/bubble/bubble_delegate.h"
 
 namespace views {
 class Widget;
 }
 
@@ skipping 22 matching lines @@
                     PaginationModel* pagination_model,
                     views::View* anchor,
                     const gfx::Point& anchor_point,
                     views::BubbleBorder::ArrowLocation arrow_location);
 
   void SetBubbleArrowLocation(
       views::BubbleBorder::ArrowLocation arrow_location);
 
   void SetAnchorPoint(const gfx::Point& anchor_point);
 
+  // Shows the UI when there are no pending icon loads. Otherwise, starts a
+  // timer to show the UI when a maximum allowed wait time has expired.
+  void ShowWhenReady();
+
   void Close();
 
   void UpdateBounds();
 
  private:
-  // Creates models to use.
-  void CreateModel();
+  class IconLoader;
+
+  // Loads icon image for the apps in the selected page of |pagination_model|.
+  // |anchor| is used to determine the image scale factor to use.
+  void PreloadIcons(PaginationModel* pagination_model,
+                    views::View* anchor);
+
+  // Invoked when |icon_loading_wait_timer_| fires.
+  void OnIconLoadingWaitTimer();
+
+  // Invoked from an IconLoader when icon loading is finished.
+  void OnItemIconLoaded(IconLoader* loader);
 
   // Overridden from views::WidgetDelegateView:
   virtual views::View* GetInitiallyFocusedView() OVERRIDE;
   virtual bool WidgetHasHitTestMask() const OVERRIDE;
   virtual void GetWidgetHitTestMask(gfx::Path* mask) const OVERRIDE;
 
   // Overridden from views::View:
   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
 
   // Overridden from AppsGridViewDelegate:
@@ skipping 13 matching lines @@
   virtual void OnWidgetClosing(views::Widget* widget) OVERRIDE;
   virtual void OnWidgetActivationChanged(views::Widget* widget, bool active)
       OVERRIDE;
 
   scoped_ptr<AppListModel> model_;
   scoped_ptr<AppListViewDelegate> delegate_;
 
   SearchBoxView* search_box_view_;  // Owned by views hierarchy.
   ContentsView* contents_view_;  // Owned by views hierarchy.
 
+  // A timer that fires when maximum allowed time to wait for icon loading has
+  // passed.
+  base::OneShotTimer<AppListView> icon_loading_wait_timer_;
+
+  ScopedVector<IconLoader> pending_icon_loaders_;
+
   DISALLOW_COPY_AND_ASSIGN(AppListView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_VIEW_H_