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

chrome/browser/icon_manager.cc

Index: chrome/browser/icon_manager.cc
diff --git a/chrome/browser/icon_manager.cc b/chrome/browser/icon_manager.cc
index 22613dbea081afbdcb3db829975da6845a1aa699..e22ccefe34dd220a9f134706eefc43da864100c1 100644
--- a/chrome/browser/icon_manager.cc
+++ b/chrome/browser/icon_manager.cc
@@ -37,7 +37,7 @@ IconManager::Handle IconManager::LoadIcon(
     const FilePath& file_name,
     IconLoader::IconSize size,
     CancelableRequestConsumerBase* consumer,
-    IconRequestCallback* callback) {
+    const IconRequestCallback& callback) {
   IconGroupID group = GetGroupIDFromFilepath(file_name);
   IconRequest* request = new IconRequest(callback);
   AddRequest(request, consumer);
@@ -83,8 +83,7 @@ bool IconManager::OnImageLoaded(IconLoader* source, gfx::Image* result) {
 
   // Inform our client that the request has completed.
   IconRequest* icon_request = client_request.request;
-  icon_request->ForwardResult(IconRequest::TupleType(icon_request->handle(),
-                                                     result));
+  icon_request->ForwardResult(icon_request->handle(), result);
   requests_.erase(rit);
 
   return true;  // Indicates we took ownership of result.