Add interface to CancelableRequest that allows use of base::Callback<>.

chrome/browser/icon_manager.h

 // Copyright (c) 2011 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.
 //
 // Class for finding and caching Windows explorer icons. The IconManager
 // lives on the UI thread but performs icon extraction work on the file thread
 // to avoid blocking the UI thread with potentially expensive COM and disk
 // operations.
 //
 // Terminology
@@ skipping 53 matching lines @@
 
   // Synchronous call to examine the internal caches for the icon. Returns the
   // icon if we have already loaded it, NULL if we don't have it and must load
   // it via 'LoadIcon'. The returned bitmap is owned by the IconManager and must
   // not be free'd by the caller. If the caller needs to modify the icon, it
   // must make a copy and modify the copy.
   gfx::Image* LookupIcon(const FilePath& file_name,
                          IconLoader::IconSize size);
 
   typedef CancelableRequestProvider::Handle Handle;
-  typedef Callback2<Handle, gfx::Image*>::Type IconRequestCallback;
+  typedef base::Callback<void(Handle, gfx::Image*)> IconRequestCallback;
 
   // Asynchronous call to lookup and return the icon associated with file. The
   // work is done on the file thread, with the callbacks running on the UI
   // thread. The return value is the 'request_id' that will be passed to the
   // client in the callback. Note: this does *not* check the cache.
   //
   // WATCH OUT: The returned bitmap pointer may be NULL if decoding failed.
   Handle LoadIcon(const FilePath& file_name,
                   IconLoader::IconSize size,
                   CancelableRequestConsumerBase* consumer,
-                  IconRequestCallback* callback);
+                  const IconRequestCallback& callback);
 
   // IconLoader::Delegate interface.
   virtual bool OnImageLoaded(IconLoader* source, gfx::Image* result);
 
   // Get the identifying string for the given file. The implementation
   // is in icon_manager_[platform].cc.
   static IconGroupID GetGroupIDFromFilepath(const FilePath& path);
 
  private:
   struct CacheKey {
@@ skipping 13 matching lines @@
 
   // Asynchronous requests that have not yet been completed.
   struct ClientRequest;
   typedef std::map<IconLoader*, ClientRequest> ClientRequests;
   ClientRequests requests_;
 
   DISALLOW_COPY_AND_ASSIGN(IconManager);
 };
 
 #endif  // CHROME_BROWSER_ICON_MANAGER_H_