Move video_encoder.h and video_decoder.h to /api and create GN targets for them

webrtc/media/engine/fakewebrtcvideoengine.h

 /*
  *  Copyright (c) 2010 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MEDIA_ENGINE_FAKEWEBRTCVIDEOENGINE_H_
 #define WEBRTC_MEDIA_ENGINE_FAKEWEBRTCVIDEOENGINE_H_
 
 #include <map>
 #include <set>
 #include <vector>
+#include <string>
 
+#include "webrtc/api/video_codecs/video_decoder.h"
+#include "webrtc/api/video_codecs/video_encoder.h"
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/gunit.h"
 #include "webrtc/base/stringutils.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/media/base/codec.h"
 #include "webrtc/media/engine/webrtcvideodecoderfactory.h"
 #include "webrtc/media/engine/webrtcvideoencoderfactory.h"
 #include "webrtc/modules/video_coding/include/video_error_codes.h"
-#include "webrtc/video_decoder.h"
-#include "webrtc/video_encoder.h"
 
 namespace cricket {
 static const int kEventTimeoutMs = 10000;
 
 // Fake class for mocking out webrtc::VideoDecoder
 class FakeWebRtcVideoDecoder : public webrtc::VideoDecoder {
  public:
   FakeWebRtcVideoDecoder() : num_frames_received_(0) {}
 
   virtual int32_t InitDecode(const webrtc::VideoCodec*, int32_t) {
@@ skipping 215 matching lines @@
   rtc::Event created_video_encoder_event_;
   std::vector<cricket::VideoCodec> codecs_;
   std::vector<FakeWebRtcVideoEncoder*> encoders_ GUARDED_BY(crit_);
   int num_created_encoders_ GUARDED_BY(crit_);
   bool encoders_have_internal_sources_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_ENGINE_FAKEWEBRTCVIDEOENGINE_H_