Fix a param signature in BrowserPluginGuest.

content/browser/browser_plugin/browser_plugin_guest.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.
 
 // A BrowserPluginGuest is the browser side of a browser <--> embedder
 // renderer channel. A BrowserPlugin (a WebPlugin) is on the embedder
 // renderer side of browser <--> embedder renderer communication.
 //
 // BrowserPluginGuest lives on the UI thread of the browser process. It has a
 // helper, BrowserPluginGuestHelper, which is a RenderViewHostObserver. The
@@ skipping 200 matching lines @@
   // Attaches this BrowserPluginGuest to the provided |embedder_web_contents|
   // and initializes the guest with the provided |params|. Attaching a guest
   // to an embedder implies that this guest's lifetime is no longer managed
   // by its opener, and it can begin loading resources.
   void Attach(WebContentsImpl* embedder_web_contents,
               BrowserPluginHostMsg_CreateGuest_Params params);
 
   // Requests geolocation permission through embedder js api.
   void AskEmbedderForGeolocationPermission(int bridge_id,
                                            const GURL& requesting_frame,
-                                           GeolocationCallback callback);
+                                           const GeolocationCallback& callback);
   // Cancels pending geolocation request.
   void CancelGeolocationRequest(int bridge_id);
   // Embedder sets permission to allow or deny geolocation request.
   void SetGeolocationPermission(int request_id, bool allowed);
 
   // Allow the embedder to call this for unhandled messages when
   // BrowserPluginGuest is already destroyed.
   static void AcknowledgeBufferPresent(int route_id,
                                        int gpu_host_id,
                                        const std::string& mailbox_name,
@@ skipping 199 matching lines @@
   // A map from request ID to instance ID for use by the New Window API.
   typedef std::map<int, int> NewWindowRequestMap;
   NewWindowRequestMap new_window_request_map_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPluginGuest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSER_PLUGIN_BROWSER_PLUGIN_GUEST_H_