Don't request missing favicon on every page request.

chrome/browser/ui/ash/launcher/launcher_favicon_loader.cc

 // 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.
 
 #include "chrome/browser/ui/ash/launcher/launcher_favicon_loader.h"
 
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/ui/ash/launcher/browser_launcher_item_controller.h"
 #include "content/public/browser/render_view_host.h"
@@ skipping 29 matching lines @@
   bool HasPendingDownloads() const;
 
   // content::WebContentObserver implementation.
   virtual void DidUpdateFaviconURL(
     int32 page_id,
     const std::vector<content::FaviconURL>& candidates) OVERRIDE;
 
  private:
   void DidDownloadFavicon(
       int id,
+      int http_status_code,
       const GURL& image_url,
       int requested_size,
       const std::vector<SkBitmap>& bitmaps);
 
   void AddFavicon(const GURL& image_url, const SkBitmap& new_bitmap);
 
   LauncherFaviconLoader::Delegate* delegate_;
 
   content::WebContents* web_contents_;
 
@@ skipping 54 matching lines @@
                    weak_ptr_factory_.GetWeakPtr()));
   }
 }
 
 bool FaviconBitmapHandler::HasPendingDownloads() const {
   return !pending_requests_.empty();
 }
 
 void FaviconBitmapHandler::DidDownloadFavicon(
     int id,
+    int http_status_code,
     const GURL& image_url,
     int requested_size,
     const std::vector<SkBitmap>& bitmaps) {
   UrlSet::iterator iter = pending_requests_.find(image_url);
   if (iter == pending_requests_.end()) {
     // Updates are received for all downloads; ignore unrequested urls.
     return;
   }
   pending_requests_.erase(iter);
 
@@ skipping 34 matching lines @@
 LauncherFaviconLoader::~LauncherFaviconLoader() {
 }
 
 SkBitmap LauncherFaviconLoader::GetFavicon() const {
   return favicon_handler_->bitmap();
 }
 
 bool LauncherFaviconLoader::HasPendingDownloads() const {
   return favicon_handler_->HasPendingDownloads();
 }