app_list: Improve initial icon loading.

ui/app_list/app_list_view.h

Index: ui/app_list/app_list_view.h
diff --git a/ui/app_list/app_list_view.h b/ui/app_list/app_list_view.h
index 76d2599ece87db1fd9d162baf99a7ae224514060..8428f16c23813304576aee5e46b8b01b4608decf 100644
--- a/ui/app_list/app_list_view.h
+++ b/ui/app_list/app_list_view.h
@@ -6,6 +6,8 @@
 #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"
@@ -48,13 +50,27 @@ class APP_LIST_EXPORT AppListView : public views::BubbleDelegateView,
 
   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;
@@ -88,6 +104,12 @@ class APP_LIST_EXPORT AppListView : public views::BubbleDelegateView,
   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);
 };