Make V4L2CaptureDelegate non-ref-counted

media/capture/video/linux/v4l2_capture_delegate.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_LINUX_V4L2_CAPTURE_DELEGATE_H_
 #define MEDIA_CAPTURE_VIDEO_LINUX_V4L2_CAPTURE_DELEGATE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/files/scoped_file.h"
 #include "base/macros.h"
-#include "base/memory/ref_counted.h"
 #include "build/build_config.h"
 #include "media/capture/video/video_capture_device.h"
 
 #if defined(OS_OPENBSD)
 #include <sys/videoio.h>
 #else
 #include <linux/videodev2.h>
 #endif
 
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace media {
 
 // Class doing the actual Linux capture using V4L2 API. V4L2 SPLANE/MPLANE
 // capture specifics are implemented in derived classes. Created and destroyed
 // on the owner's thread, otherwise living and operating on |v4l2_task_runner_|.

[chfremer, 2017/04/12 17:13:46]

No longer accurate. We are now destroying the instances on the
|v4l2_task_runner_| as well, which is essential for the correctness of the usage
of the WeakPtrFactory. PLease update the comment.

[Chandan, 2017/04/13 09:06:07]

Done.

-// TODO(mcasas): Make this class a non-ref-counted.
-class CAPTURE_EXPORT V4L2CaptureDelegate final
-    : public base::RefCountedThreadSafe<V4L2CaptureDelegate> {
+class CAPTURE_EXPORT V4L2CaptureDelegate final {
  public:
   // Retrieves the #planes for a given |fourcc|, or 0 if unknown.
   static size_t GetNumPlanesForFourCc(uint32_t fourcc);
   // Returns the Chrome pixel format for |v4l2_fourcc| or PIXEL_FORMAT_UNKNOWN.
   static VideoPixelFormat V4l2FourCcToChromiumPixelFormat(
       uint32_t v4l2_fourcc);
 
   // Composes a list of usable and supported pixel formats, in order of
   // preference, with MJPEG prioritised depending on |prefer_mjpeg|.
   static std::list<uint32_t> GetListOfUsableFourCcs(bool prefer_mjpeg);
 
   V4L2CaptureDelegate(
       const VideoCaptureDeviceDescriptor& device_descriptor,
       const scoped_refptr<base::SingleThreadTaskRunner>& v4l2_task_runner,
       int power_line_frequency);
+  ~V4L2CaptureDelegate();
 
   // Forward-to versions of VideoCaptureDevice virtual methods.
   void AllocateAndStart(int width,
                         int height,
                         float frame_rate,
                         std::unique_ptr<VideoCaptureDevice::Client> client);
   void StopAndDeAllocate();
 
   void TakePhoto(VideoCaptureDevice::TakePhotoCallback callback);
 
   void GetPhotoCapabilities(
       VideoCaptureDevice::GetPhotoCapabilitiesCallback callback);
   void SetPhotoOptions(mojom::PhotoSettingsPtr settings,
                        VideoCaptureDevice::SetPhotoOptionsCallback callback);
 
   void SetRotation(int rotation);
 
  private:
   friend class V4L2CaptureDelegateTest;
 
-  friend class base::RefCountedThreadSafe<V4L2CaptureDelegate>;
-  ~V4L2CaptureDelegate();
-
   class BufferTracker;
 
   // VIDIOC_QUERYBUFs a buffer from V4L2, creates a BufferTracker for it and
   // enqueues it (VIDIOC_QBUF) back into V4L2.
   bool MapAndQueueBuffer(int index);
 
   void DoCapture();
 
   void SetErrorState(const tracked_objects::Location& from_here,
                      const std::string& reason);
@@ skipping 14 matching lines @@
   std::vector<scoped_refptr<BufferTracker>> buffer_tracker_pool_;
 
   bool is_capturing_;
   int timeout_count_;
 
   base::TimeTicks first_ref_time_;
 
   // Clockwise rotation in degrees. This value should be 0, 90, 180, or 270.
   int rotation_;
 
+  base::WeakPtrFactory<V4L2CaptureDelegate> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(V4L2CaptureDelegate);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_VIDEO_LINUX_V4L2_CAPTURE_DELEGATE_H_