Fix a param signature in BrowserPluginGuest.

content/browser/browser_plugin/browser_plugin_guest.cc

 // 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.
 
 #include "content/browser/browser_plugin/browser_plugin_guest.h"
 
 #include <algorithm>
 
 #include "base/message_loop.h"
 #include "base/string_util.h"
@@ skipping 482 matching lines @@
   SendMessageToEmbedder(
       new BrowserPluginMsg_LoadRedirect(instance_id(),
                                         old_url,
                                         new_url,
                                         is_top_level));
 }
 
 void BrowserPluginGuest::AskEmbedderForGeolocationPermission(
     int bridge_id,
     const GURL& requesting_frame,
-    GeolocationCallback callback) {
+    const GeolocationCallback& callback) {
   if (geolocation_request_callback_map_.size() >=
           kNumMaxOutstandingPermissionRequests) {
     // Deny the geolocation request.
     callback.Run(false);
     return;
   }
   int request_id = next_permission_request_id_++;
   geolocation_request_callback_map_[request_id] = callback;
 
   base::DictionaryValue request_info;
@@ skipping 704 matching lines @@
     LOG(INFO) << "Guest not found. Instance ID: " << instance_id;
     return;
   }
   if (!should_allow)
     guest->Destroy();
   // If we do not destroy the guest then we allow the new window.
   new_window_request_map_.erase(new_window_request_iter);
 }
 
 }  // namespace content