Ensure that WebRTC AEC recording checkbox is not set if cancelling file dialog.

content/browser/media/webrtc_internals_message_handler.cc

 // Copyright (c) 2013 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/media/webrtc_internals_message_handler.h"
 
 #include "content/browser/media/webrtc_internals.h"
 #include "content/common/media/peer_connection_tracker_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_frame_host.h"
@@ skipping 57 matching lines @@
     RenderFrameHost* host = web_ui()->GetWebContents()->GetMainFrame();
     if (host)
       host->ExecuteJavaScript(script);
   }
 }
 
 void WebRTCInternalsMessageHandler::OnUpdate(const std::string& command,
                                              const base::Value* args) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   std::vector<const base::Value*> args_vector;
-  args_vector.push_back(args);
+  if (args)
+    args_vector.push_back(args);
   base::string16 update = WebUI::GetJavascriptCall(command, args_vector);
 
   RenderFrameHost* host = web_ui()->GetWebContents()->GetMainFrame();
   if (host)
     host->ExecuteJavaScript(update);
 }
 
 }  // namespace content