Eliminate all UI thread decoding of extension images....

chrome/browser/cocoa/extensions/browser_action_button.mm

 // Copyright (c) 2010 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.
 
 #import "chrome/browser/cocoa/extensions/browser_action_button.h"
 
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/cocoa/extensions/extension_action_context_menu.h"
 #include "chrome/browser/extensions/image_loading_tracker.h"
 #include "chrome/common/extensions/extension.h"
@@ skipping 24 matching lines @@
 const CGFloat kShadowOffset = 2.0;
 }  // anonymous namespace
 
 // A helper class to bridge the asynchronous Skia bitmap loading mechanism to
 // the extension's button.
 class ExtensionImageTrackerBridge : public NotificationObserver,
                                     public ImageLoadingTracker::Observer {
  public:
   ExtensionImageTrackerBridge(BrowserActionButton* owner, Extension* extension)
       : owner_(owner),
-        tracker_(NULL) {
+        tracker_(this) {
     // The Browser Action API does not allow the default icon path to be
     // changed at runtime, so we can load this now and cache it.
     std::string path = extension->browser_action()->default_icon_path();
     if (!path.empty()) {
-      tracker_ = new ImageLoadingTracker(this, 1);
-      tracker_->PostLoadImageTask(extension->GetResource(path),
+      tracker_.LoadImage(extension->GetResource(path),
           gfx::Size(Extension::kBrowserActionIconMaxSize,
                     Extension::kBrowserActionIconMaxSize));
     }
     registrar_.Add(this, NotificationType::EXTENSION_BROWSER_ACTION_UPDATED,
                    Source<ExtensionAction>(extension->browser_action()));
   }
 
   ~ExtensionImageTrackerBridge() {
-    if (tracker_)
-      tracker_->StopTrackingImageLoad();
   }
 
   // ImageLoadingTracker::Observer implementation.
-  void OnImageLoaded(SkBitmap* image, size_t index) {
+  void OnImageLoaded(SkBitmap* image, ExtensionResource resource, int index) {
     if (image)
       [owner_ setDefaultIcon:gfx::SkBitmapToNSImage(*image)];
-    tracker_ = NULL;
     [owner_ updateState];
   }
 
   // Overridden from NotificationObserver.
   void Observe(NotificationType type,
                const NotificationSource& source,
                const NotificationDetails& details) {
     if (type == NotificationType::EXTENSION_BROWSER_ACTION_UPDATED)
       [owner_ updateState];
     else
       NOTREACHED();
   }
 
  private:
   // Weak. Owns us.
   BrowserActionButton* owner_;
 
-  // Loads the button's icons for us on the file thread. Weak.
-  ImageLoadingTracker* tracker_;
+  // Loads the button's icons for us on the file thread.
+  ImageLoadingTracker tracker_;
 
   // Used for registering to receive notifications and automatic clean up.
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionImageTrackerBridge);
 };
 
 @interface BrowserActionCell(Internals)
 - (void)setIconShadow;
 - (void)drawBadgeWithinFrame:(NSRect)frame;
@@ skipping 149 matching lines @@
   [super drawInteriorWithFrame:cellFrame inView:controlView];
   cellFrame.origin.y += kBrowserActionBadgeOriginYOffset;
   [self drawBadgeWithinFrame:cellFrame];
   [NSGraphicsContext restoreGraphicsState];
 }
 
 @synthesize tabId = tabId_;
 @synthesize extensionAction = extensionAction_;
 
 @end