[chrome.displaySource] Add client thread checks to encoders.

extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.cc

 // Copyright 2016 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 "extensions/renderer/api/display_source/wifi_display/wifi_display_video_encoder.h"
 
 #include "base/logging.h"
 
 namespace extensions {
 
@@ skipping 13 matching lines @@
 // static
 void WiFiDisplayVideoEncoder::Create(
     const InitParameters& params,
     const VideoEncoderCallback& encoder_callback) {
   CreateVEA(params, encoder_callback);
 }
 
 void WiFiDisplayVideoEncoder::InsertRawVideoFrame(
     const scoped_refptr<media::VideoFrame>& video_frame,
     base::TimeTicks reference_time) {
+  DCHECK(client_thread_checker_.CalledOnValidThread());

[Mikhail, 2016/04/27 11:07:48]

how about audio encoder and the implementations (vea, svc, lpcm)?

   DCHECK(!encoded_callback_.is_null());
   media_task_runner_->PostTask(
       FROM_HERE, base::Bind(&WiFiDisplayVideoEncoder::InsertFrameOnMediaThread,
                             this, video_frame, reference_time, send_idr_));
   send_idr_ = false;
 }
 
 void WiFiDisplayVideoEncoder::RequestIDRPicture() {
+  DCHECK(client_thread_checker_.CalledOnValidThread());
   send_idr_ = true;
 }
 
 }  // namespace extensions