Add flag for enabling WebRTC AEC debug recordings.

content/renderer/media/rtc_media_constraints.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.
 
 #ifndef CONTENT_RENDERER_MEDIA_RTC_MEDIA_CONSTRAINTS_H_
 #define CONTENT_RENDERER_MEDIA_RTC_MEDIA_CONSTRAINTS_H_
 
 #include "base/compiler_specific.h"
 #include "third_party/libjingle/source/talk/app/webrtc/mediaconstraintsinterface.h"
 
 namespace WebKit {
 class WebMediaConstraints;
 }
 
 namespace content {
 
 // RTCMediaConstraints acts as a glue layer between WebKits MediaConstraints and
 // libjingle webrtc::MediaConstraintsInterface.
 // Constraints are used by PeerConnection and getUserMedia API calls.
 class RTCMediaConstraints : public webrtc::MediaConstraintsInterface {
  public:
   explicit RTCMediaConstraints(
       const WebKit::WebMediaConstraints& constraints);
   virtual ~RTCMediaConstraints();
   virtual const Constraints& GetMandatory() const OVERRIDE;
   virtual const Constraints& GetOptional() const OVERRIDE;
+  void AddOptional(const std::string& key, const std::string& value);
 
  protected:
   Constraints mandatory_;
   Constraints optional_;
 };
 
 }  // namespace content
 
 
 #endif  // CONTENT_RENDERER_MEDIA_RTC_MEDIA_CONSTRAINTS_H_