Remove unused 'last_key_frame_picture_id' field.

webrtc/modules/video_coding/codecs/vp8/vp8_impl.h

 /*
  *  Copyright (c) 2012 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.
  *
  * WEBRTC VP8 wrapper interface
@@ skipping 84 matching lines @@
   EncodedImageCallback* encoded_complete_callback_;
   VideoCodec codec_;
   bool inited_;
   int64_t timestamp_;
   int qp_max_;
   int cpu_speed_default_;
   int number_of_cores_;
   uint32_t rc_max_intra_target_;
   std::vector<TemporalLayers*> temporal_layers_;
   std::vector<uint16_t> picture_id_;
-  std::vector<int> last_key_frame_picture_id_;
   std::vector<bool> key_frame_request_;
   std::vector<bool> send_stream_;
   std::vector<int> cpu_speed_;
   std::vector<vpx_image_t> raw_images_;
   std::vector<EncodedImage> encoded_images_;
   std::vector<vpx_codec_ctx_t> encoders_;
   std::vector<vpx_codec_enc_cfg_t> configurations_;
   std::vector<vpx_rational_t> downsampling_factors_;
 };
 
@@ skipping 29 matching lines @@
   bool inited_;
   vpx_codec_ctx_t* decoder_;
   int propagation_cnt_;
   int last_frame_width_;
   int last_frame_height_;
   bool key_frame_required_;
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_CODECS_VP8_VP8_IMPL_H_