Add a class to replace ImageLoadingTracker with a nicer API.

chrome/browser/extensions/extension_system.h

Index: chrome/browser/extensions/extension_system.h
diff --git a/chrome/browser/extensions/extension_system.h b/chrome/browser/extensions/extension_system.h
index 93cec349945303769fb860f751c04081e95975fd..b703b773b60ac1ff00aec15d6f1fa6186c04f1d4 100644
--- a/chrome/browser/extensions/extension_system.h
+++ b/chrome/browser/extensions/extension_system.h
@@ -30,6 +30,7 @@ class EventRouter;
 class Extension;
 class ExtensionPrefs;
 class ExtensionSystemSharedFactory;
+class ImageLoader;
 class LazyBackgroundTaskQueue;
 class ManagementPolicy;
 class MessageService;
@@ -104,6 +105,9 @@ class ExtensionSystem : public ProfileKeyedService {
   // The RulesRegistryService is created at startup.
   virtual RulesRegistryService* rules_registry_service() = 0;
 
+  // Returns the ImageLoader that should be used to load extension images.
+  virtual ImageLoader* image_loader() = 0;
+
   // The SerialConnection ResourceManager is created at startup.
   virtual ApiResourceManager<SerialConnection>*
   serial_connection_manager() = 0;
@@ -154,8 +158,9 @@ class ExtensionSystemImpl : public ExtensionSystem {
   virtual ExtensionDevToolsManager* devtools_manager() OVERRIDE;
   virtual ExtensionProcessManager* process_manager() OVERRIDE;
   virtual AlarmManager* alarm_manager() OVERRIDE;
-  virtual StateStore* state_store() OVERRIDE;
-  virtual ShellWindowGeometryCache* shell_window_geometry_cache() OVERRIDE;
+  virtual StateStore* state_store() OVERRIDE;  // shared
+  virtual ShellWindowGeometryCache* shell_window_geometry_cache()
+      OVERRIDE;  // shared
   virtual LazyBackgroundTaskQueue* lazy_background_task_queue()
       OVERRIDE;  // shared
   virtual ExtensionInfoMap* info_map() OVERRIDE;  // shared
@@ -163,6 +168,7 @@ class ExtensionSystemImpl : public ExtensionSystem {
   virtual EventRouter* event_router() OVERRIDE;  // shared
   virtual RulesRegistryService* rules_registry_service()
       OVERRIDE;  // shared
+  virtual ImageLoader* image_loader() OVERRIDE;  // shared
   virtual ApiResourceManager<SerialConnection>* serial_connection_manager()
       OVERRIDE;
   virtual ApiResourceManager<Socket>* socket_manager() OVERRIDE;
@@ -204,6 +210,7 @@ class ExtensionSystemImpl : public ExtensionSystem {
     LazyBackgroundTaskQueue* lazy_background_task_queue();
     MessageService* message_service();
     EventRouter* event_router();
+    ImageLoader* image_loader();
 
    private:
     Profile* profile_;
@@ -223,6 +230,7 @@ class ExtensionSystemImpl : public ExtensionSystem {
     scoped_ptr<LazyBackgroundTaskQueue> lazy_background_task_queue_;
     scoped_ptr<MessageService> message_service_;
     scoped_ptr<EventRouter> extension_event_router_;
+    scoped_ptr<ImageLoader> image_loader_;
     scoped_ptr<NavigationObserver> navigation_observer_;
   };