media: add video capture device for ARC++ camera HAL v3

media/capture/video/chromeos/video_capture_device_arc_chromeos.h

+// Copyright 2017 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_CHROMEOS_VIDEO_CAPTURE_DEVICE_CHROMEOS_H_

[Pawel Osciak, 2017/06/13 08:40:16]

MEDIA_CAPTURE_VIDEO_CHROMEOS_VIDEO_CAPTURE_DEVICE_ARC_CHROMEOS_H_ ?

[jcliang, 2017/06/14 04:46:08]

Done.

+#define MEDIA_CAPTURE_VIDEO_CHROMEOS_VIDEO_CAPTURE_DEVICE_CHROMEOS_H_
+
+#include <stdint.h>

[Pawel Osciak, 2017/06/13 08:40:16]

Is this header needed?

[jcliang, 2017/06/14 04:46:07]

Removed.

+
+#include <memory>
+#include <string>

[Pawel Osciak, 2017/06/13 08:40:16]

Is this header needed?

[jcliang, 2017/06/14 04:46:07]

Removed.

+
+#include "base/macros.h"
+#include "base/threading/thread.h"
+#include "media/capture/video/chromeos/display_rotation_observer.h"
+#include "media/capture/video/chromeos/mojo/arc_camera3.mojom.h"
+#include "media/capture/video/video_capture_device.h"
+#include "media/capture/video/video_capture_device_descriptor.h"
+#include "media/capture/video_capture_types.h"
+
+namespace display {
+
+class Display;
+
+}  // namespace display
+
+namespace media {
+
+class CameraHalDelegate;
+class CameraDeviceDelegate;
+
+// Implementation of VideoCaptureDevice for ChromeOS with ARC++ camera HALv3.
+class CAPTURE_EXPORT VideoCaptureDeviceArcChromeOS final
+    : public VideoCaptureDevice,
+      public DisplayRotationObserver {
+ public:
+  VideoCaptureDeviceArcChromeOS(
+      scoped_refptr<base::SingleThreadTaskRunner>
+          task_runner_for_screen_observer,
+      const VideoCaptureDeviceDescriptor& device_descriptor,
+      scoped_refptr<CameraHalDelegate> camera_hal_delegate);
+
+  ~VideoCaptureDeviceArcChromeOS() final;
+
+  // VideoCaptureDevice implementation.
+  void AllocateAndStart(const VideoCaptureParams& params,
+                        std::unique_ptr<Client> client) final;
+  void StopAndDeAllocate() final;
+  void TakePhoto(TakePhotoCallback callback) final;
+  void GetPhotoCapabilities(GetPhotoCapabilitiesCallback callback) final;
+  void SetPhotoOptions(mojom::PhotoSettingsPtr settings,
+                       SetPhotoOptionsCallback callback) final;
+
+ private:
+  // DisplayRotationDelegate implementation.
+  void SetDisplayRotation(const display::Display& display) final;
+  void SetRotation(int rotation);
+
+  const VideoCaptureDeviceDescriptor device_descriptor_;
+
+  // A reference to the CameraHalDelegate instance in the VCD factory.  This is
+  // used by AllocateAndStart to query camera info and create the camera device.
+  const scoped_refptr<CameraHalDelegate> camera_hal_delegate_;
+
+  // A reference to the thread that all the VideoCaptureDevice interface methods
+  // are expected to be called on.
+  const scoped_refptr<base::SingleThreadTaskRunner> capture_task_runner_;
+
+  // The thread that all the Mojo operations of |camera_device_delegate_| take
+  // place.  Started in AllocateAndStart and stopped in StopAndDeAllocate, where
+  // the access to the base::Thread methods are sequenced on
+  // |capture_task_runner_|.
+  base::Thread camera_device_ipc_thread_;
+
+  // Internal delegate doing the actual capture setting, buffer allocation and
+  // circulation with the camera HAL. Created in AllocateAndStart and deleted in
+  // StopAndDeAllocate on |capture_task_runner_|.  All methods of
+  // |camera_device_delegate_| operate on |camera_device_ipc_thread_|.
+  scoped_refptr<CameraDeviceDelegate> camera_device_delegate_;

[Pawel Osciak, 2017/06/13 08:40:16]

Would it make sense to consider unique_ptr and posting to weak pointers instead?
Unless I'm missing something, if the delegate is not used by anyone else, if
this class is destroyed, we could just invalidate the weak pointers and drop any
callbacks.

Or actually, if camera_device_ipc_thread_ is fully owned and used only in this
class (which it appears so?), then we could just post to unretained, just
ensuring that the thread got destroyed before the delegate...?

[jcliang, 2017/06/14 04:46:08]

The CameraDeviceDelegate posts itself to the ipc thread on CameraHalDelegate
when it needs to query camera info (in AllocateAndStart) and open camera devices
(in OnGotCameraInfo), so it needs to be a scoped_refptr here.

I have some rough ideas to split it to two classes: one for creating the device
on the ipc thread of CameraHalDelegate, and one for talking to the device on the
ipc thread of CameraDeviceDelegate. This will need some refactor of the current
code. I'll submit another CL to improve this if it works.

+
+  scoped_refptr<ScreenObserverDelegate> screen_observer_delegate_;
+  const VideoFacingMode lens_facing_;
+  const int camera_orientation_;
+  // Whether the incoming frames should rotate when the device rotates.
+  const bool rotates_with_device_;
+  int rotation_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(VideoCaptureDeviceArcChromeOS);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CAPTURE_VIDEO_CHROMEOS_VIDEO_CAPTURE_DEVICE_CHROMEOS_H_