[Favicon] Stop caching the default favicon

chrome/browser/ui/webui/favicon_source.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 CHROME_BROWSER_UI_WEBUI_FAVICON_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_FAVICON_SOURCE_H_
 
 #include <map>
 #include <string>
 
@@ skipping 87 matching lines @@
 
   // Called when the favicon data is missing to perform additional checks to
   // locate the resource.
   // |request| contains information for the failed request.
   // Returns true if the missing resource is found.
   virtual bool HandleMissingResource(const IconRequest& request);
 
   Profile* profile_;
 
  private:
-  // Defines the allowed pixel sizes for requested favicons.
+  // Defines the pixel sizes for requested favicons.
   enum IconSize {
-    SIZE_16,
-    SIZE_32,
-    SIZE_64,
-    NUM_SIZES
+    SIZE_NOT_EXISTS = 0,
+    SIZE_16 = 16,
+    SIZE_32 = 32,
+    SIZE_64 = 64
   };
 
   // Called when favicon data is available from the history backend.
   void OnFaviconDataAvailable(
       const IconRequest& request,
       const favicon_base::FaviconRawBitmapResult& bitmap_result);
 
   // Sends the 16x16 DIP 1x default favicon.
   void SendDefaultResponse(
       const content::URLDataSource::GotDataCallback& callback);
 
   // Sends the default favicon.
   void SendDefaultResponse(const IconRequest& request);
 
   base::CancelableTaskTracker cancelable_task_tracker_;
 
-  // Raw PNG representations of favicons of each size to show when the favicon
-  // database doesn't have a favicon for a webpage. Indexed by IconSize values.
-  scoped_refptr<base::RefCountedMemory> default_favicons_[NUM_SIZES];
-
   // The favicon_base::IconTypes of icon that this FaviconSource handles.
   int icon_types_;
 
   DISALLOW_COPY_AND_ASSIGN(FaviconSource);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_FAVICON_SOURCE_H_