Allow WebrtcDummyVideoEncoder::RegisterEncodeCompleteCallback to take a nullptr.

remoting/protocol/webrtc_dummy_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 "remoting/protocol/webrtc_dummy_video_encoder.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 35 matching lines @@
         return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
       }
     }
   }
   state_ = kInitialized;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 int32_t WebrtcDummyVideoEncoder::RegisterEncodeCompleteCallback(
     webrtc::EncodedImageCallback* callback) {
-  DCHECK(callback);
   base::AutoLock lock(lock_);
   encoded_callback_ = callback;
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
 int32_t WebrtcDummyVideoEncoder::Release() {
   base::AutoLock lock(lock_);
   encoded_callback_ = nullptr;
   return WEBRTC_VIDEO_CODEC_OK;
 }
@@ skipping 89 matching lines @@
 
   webrtc::RTPFragmentationHeader header;
   memset(&header, 0, sizeof(header));
 
   header.VerifyAndAllocateFragmentationHeader(1);
   header.fragmentationOffset[0] = 0;
   header.fragmentationLength[0] = buffer_size;
   header.fragmentationPlType[0] = 0;
   header.fragmentationTimeDiff[0] = 0;
 
+  DCHECK(encoded_callback_);
   return encoded_callback_->OnEncodedImage(encoded_image, &codec_specific_info,
                                            &header);
 }
 
 WebrtcDummyVideoEncoderFactory::WebrtcDummyVideoEncoderFactory()
     : main_task_runner_(base::ThreadTaskRunnerHandle::Get()) {
   // TODO(isheriff): These do not really affect anything internally
   // in webrtc.
   codecs_.push_back(cricket::VideoCodec("VP8"));
   codecs_.push_back(cricket::VideoCodec("VP9"));
@@ skipping 67 matching lines @@
 void WebrtcDummyVideoEncoderFactory::SetVideoChannelStateObserver(
     base::WeakPtr<VideoChannelStateObserver> video_channel_state_observer) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   DCHECK(encoders_.empty());
   base::AutoLock lock(lock_);
   video_channel_state_observer_ = video_channel_state_observer;
 }
 
 }  // namespace protocol
 }  // namespace remoting