[Mojo Video Capture] Retire buffers when Android Chromium goes to the background

media/capture/video/video_capture_device_client.h

 // Copyright 2015 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.
 
 #ifndef MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_CLIENT_H_
 #define MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_CLIENT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
+#include <set>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/threading/thread_collision_warner.h"
 #include "media/capture/capture_export.h"
 #include "media/capture/video/video_capture_device.h"
 
 namespace media {
 class VideoCaptureBufferPool;
 class VideoFrameReceiver;
 class VideoCaptureJpegDecoder;
 
 using VideoCaptureJpegDecoderFactoryCB =
     base::Callback<std::unique_ptr<VideoCaptureJpegDecoder>()>;
@@ skipping 70 matching lines @@
   // A branch of OnIncomingCapturedData for Y16 frame_format.pixel_format.
   void OnIncomingCapturedY16Data(const uint8_t* data,
                                  int length,
                                  const VideoCaptureFormat& frame_format,
                                  base::TimeTicks reference_time,
                                  base::TimeDelta timestamp,
                                  int frame_feedback_id);
 
   // The receiver to which we post events.
   const std::unique_ptr<VideoFrameReceiver> receiver_;
+  std::set<int> buffer_ids_known_by_receiver_;
 
   const VideoCaptureJpegDecoderFactoryCB jpeg_decoder_factory_callback_;
   std::unique_ptr<VideoCaptureJpegDecoder> external_jpeg_decoder_;
 
   // Whether |external_jpeg_decoder_| has been initialized.
   bool external_jpeg_decoder_initialized_;
 
   // The pool of shared-memory buffers used for capturing.
   const scoped_refptr<VideoCaptureBufferPool> buffer_pool_;
 
 #if DCHECK_IS_ON()
   // Counter used to track the number of times consecutive capture buffers are
   // dropped.
   int dropped_frame_counter_ = 0;
 
   static const int kMaxDroppedFrames = 150;
 #endif  // DCHECK_IS_ON()
 
   media::VideoPixelFormat last_captured_pixel_format_;
 
+  // Thread collision warner to ensure that producer-facing API is not called
+  // concurrently. Producers are allowed to call from multiple threads, but not
+  // concurrently.
+  DFAKE_MUTEX(call_from_producer_);

[mcasas, 2017/01/20 22:41:32]

Ooooh this is brilliant!

[chfremer, 2017/01/25 23:45:23]

Acknowledged.

+
   DISALLOW_COPY_AND_ASSIGN(VideoCaptureDeviceClient);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_VIDEO_VIDEO_CAPTURE_DEVICE_CLIENT_H_