Fix VideoToolbox backgrounding issues

webrtc/modules/video_coding/codecs/h264/h264_video_toolbox_nalu.h

 /*
  *  Copyright (c) 2015 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.
  *
  */
@@ skipping 26 matching lines @@
 // VideoToolbox decoder. The RTP buffer is in annex b format whereas the sample
 // buffer is in avcc format.
 // If |is_keyframe| is true then |video_format| is ignored since the format will
 // be read from the buffer. Otherwise |video_format| must be provided.
 // Caller is responsible for releasing the created sample buffer.
 bool H264AnnexBBufferToCMSampleBuffer(const uint8_t* annexb_buffer,
                                       size_t annexb_buffer_size,
                                       CMVideoFormatDescriptionRef video_format,
                                       CMSampleBufferRef* out_sample_buffer);
 
+// Returns true if the type of the first NALU in the supplied Annex B buffer is
+// the SPS type.
+bool H264AnnexBBufferHasVideoFormatDescription(const uint8_t* annexb_buffer,
+                                               size_t annexb_buffer_size);
+
+// Returns a video format description created from the sps/pps information in
+// the Annex B buffer. If there is no such information, nullptr is returned.
+// The caller is responsible for releasing the description.
+CMVideoFormatDescriptionRef CreateVideoFormatDescription(
+    const uint8_t* annexb_buffer,
+    size_t annexb_buffer_size);
+
 // Helper class for reading NALUs from an RTP Annex B buffer.
 class AnnexBBufferReader final {
  public:
   AnnexBBufferReader(const uint8_t* annexb_buffer, size_t length);
   ~AnnexBBufferReader() {}
   AnnexBBufferReader(const AnnexBBufferReader& other) = delete;
   void operator=(const AnnexBBufferReader& other) = delete;
 
   // Returns a pointer to the beginning of the next NALU slice without the
   // header bytes and its length. Returns false if no more slices remain.
@@ skipping 33 matching lines @@
  private:
   uint8_t* const start_;
   size_t offset_;
   const size_t length_;
 };
 
 }  // namespace webrtc
 
 #endif  // defined(WEBRTC_VIDEO_TOOLBOX_SUPPORTED)
 #endif  // WEBRTC_MODULES_VIDEO_CODING_CODECS_H264_H264_VIDEO_TOOLBOX_NALU_H_