Makes a handful of DataSources not replace the existing

chrome/browser/dom_ui/web_ui_favicon_source.cc

 // 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.
 
 #include "chrome/browser/dom_ui/web_ui_favicon_source.h"
 
 #include "base/callback.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/url_constants.h"
 #include "grit/app_resources.h"
@@ skipping 36 matching lines @@
     SendResponse(request_id, NULL);
   }
 }
 
 std::string WebUIFavIconSource::GetMimeType(const std::string&) const {
   // We need to explicitly return a mime type, otherwise if the user tries to
   // drag the image they get no extension.
   return "image/png";
 }
 
+bool WebUIFavIconSource::ShouldReplaceExistingSource() const {
+  // Leave the existing DataSource in place, otherwise we'll drop any pending
+  // requests on the floor.
+  return false;
+}
+
 void WebUIFavIconSource::OnFavIconDataAvailable(
     FaviconService::Handle request_handle,
     bool know_favicon,
     scoped_refptr<RefCountedMemory> data,
     bool expired,
     GURL icon_url) {
   FaviconService* favicon_service =
       profile_->GetFaviconService(Profile::EXPLICIT_ACCESS);
   int request_id = cancelable_consumer_.GetClientData(favicon_service,
                                                       request_handle);
 
   if (know_favicon && data.get() && data->size()) {
     // Forward the data along to the networking system.
     SendResponse(request_id, data);
   } else {
     SendDefaultResponse(request_id);
   }
 }
 
 void WebUIFavIconSource::SendDefaultResponse(int request_id) {
   if (!default_favicon_.get()) {
     default_favicon_ =
         ResourceBundle::GetSharedInstance().LoadDataResourceBytes(
             IDR_DEFAULT_FAVICON);
   }
 
   SendResponse(request_id, default_favicon_);
 }