Make favicons for about:history and about:bookmarks switch from lodpi to hidpi when dragging browser

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 34 matching lines @@
 
   virtual std::string GetMimeType(const std::string&) const OVERRIDE;
 
   virtual bool ShouldReplaceExistingSource() const OVERRIDE;
 
  protected:
   virtual ~FaviconSource();
 
   Profile* profile_;
 
- private:
   // Defines the allowed pixel sizes for requested favicons.
   enum IconSize {
     SIZE_16,
     SIZE_32,
     SIZE_64,
     NUM_SIZES
   };
 
   struct IconRequest {
     IconRequest()
       : request_id(0),
+        request_path(""),
         size_in_dip(gfx::kFaviconSize),
         scale_factor(ui::SCALE_FACTOR_NONE) {
     }
-    IconRequest(int id, int size, ui::ScaleFactor scale)
+    IconRequest(int id,
+                const std::string& path,
+                int size,
+                ui::ScaleFactor scale)
       : request_id(id),
+        request_path(path),
         size_in_dip(size),
         scale_factor(scale) {
     }
     int request_id;
+    std::string request_path;
     int size_in_dip;
     ui::ScaleFactor scale_factor;
   };
 
+  // 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);
+
+ private:
   void Init(Profile* profile, IconType type);
 
   // Called when favicon data is available from the history backend.
   void OnFaviconDataAvailable(
       const IconRequest& request,
       const history::FaviconBitmapResult& bitmap_result);
 
   // Sends the default favicon.
   void SendDefaultResponse(const IconRequest& request);
 
   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 history::IconTypes of icon that this FaviconSource handles.
   int icon_types_;
 
   DISALLOW_COPY_AND_ASSIGN(FaviconSource);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_FAVICON_SOURCE_H_