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

media/capture/video/chromeos/camera_hal_delegate.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_CAMERA_HAL_DELEGATE_H_
+#define MEDIA_CAPTURE_VIDEO_CHROMEOS_CAMERA_HAL_DELEGATE_H_
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "base/macros.h"
+#include "base/sequence_checker.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread.h"
+#include "media/capture/video/chromeos/mojo/arc_camera3.mojom.h"
+#include "media/capture/video/video_capture_device_factory.h"
+#include "media/capture/video_capture_types.h"
+#include "mojo/public/cpp/bindings/binding.h"
+
+namespace media {
+
+// CameraHalDelegate is the component which does Mojo IPCs to the camera HAL
+// process on Chrome OS to access the module-level camera functionalities such
+// as camera device info look-up and opening camera devices.
+//
+// CameraHalDelegate is refcounted because VideoCaptureDeviceFactoryChromeOS and
+// CameraDeviceDelegate both need to reference CameraHalDelegate, and
+// VideoCaptureDeviceFactoryChromeOS may be destroyed while CameraDeviceDelegate
+// is still alive.
+class CAPTURE_EXPORT CameraHalDelegate final
+    : public base::RefCountedThreadSafe<CameraHalDelegate>,
+      public arc::mojom::CameraModuleCallbacks {
+ public:
+  // All the Mojo IPC operations happen on |module_task_runner|.

[chfremer, 2017/05/31 18:30:41]

Both here and in the class-level description I don't really understand what
"module" refers to.
As a result, I don't have a clear understanding of why |module_task_runnner| is
a suitable name. If it is used exclusively for IPC operations, would
|ipc_task_runner| also be a suitable name?

[jcliang, 2017/06/01 17:11:17]

Agreed. I'll change this to ipc_task_runner.

+  explicit CameraHalDelegate(
+      scoped_refptr<base::SingleThreadTaskRunner> module_task_runner);
+
+  // Establishes the Mojo IPC channel to the camera HAL adapter.  This method
+  // should be called before any other methods of CameraHalDelegate is called.
+  bool StartCameraModuleIpc();
+
+  // Resets |camera_module_| and |camera_module_callbacks_|.
+  void Reset();
+
+  // Delegation methods for the VideoCaptureDeviceFactory interface.  These
+  // methods are called by VideoCaptureDeviceFactoryChromeOS directly.  They
+  // operate on the same thread that the VideoCaptureDeviceFactoryChromeOS runs
+  // on.
+  std::unique_ptr<VideoCaptureDevice> CreateDevice(
+      scoped_refptr<base::SingleThreadTaskRunner>
+          task_runner_for_screen_observer,
+      const VideoCaptureDeviceDescriptor& device_descriptor);
+  void GetSupportedFormats(
+      const VideoCaptureDeviceDescriptor& device_descriptor,
+      VideoCaptureFormats* supported_formats);
+  void GetDeviceDescriptors(VideoCaptureDeviceDescriptors* device_descriptors);
+
+  // Asynchronous method to get the camera info of |camera_id|.  This method may
+  // be called on any thread.
+  using GetCameraInfoCallback =
+      base::Callback<void(int32_t, arc::mojom::CameraInfoPtr)>;
+  void GetCameraInfo(int32_t camera_id, const GetCameraInfoCallback& callback);
+
+  // Asynchronous method to open the camera device designated by |camera_id|.
+  // This method may be called on any thread; |callback| will run on
+  // |module_task_runner_|.
+  using OpenDeviceCallback = base::Callback<void(int32_t)>;
+  void OpenDevice(int32_t camera_id,
+                  arc::mojom::Camera3DeviceOpsRequest device_ops_request,
+                  const OpenDeviceCallback& callback);
+
+ private:
+  friend class base::RefCountedThreadSafe<CameraHalDelegate>;
+
+  ~CameraHalDelegate();
+
+  friend class CameraHalDelegateTest;
+  friend class CameraDeviceDelegateTest;
+  void StartForTesting(arc::mojom::CameraModulePtrInfo info);
+
+  // Resets the Mojo interface and bindings.
+  void ResetMojoInterfaceOnModuleThread();
+
+  // Internal method to update the camera info for all built-in cameras. Runs on
+  // the same thread as CreateDevice, GetSupportedFormats, and
+  // GetDeviceDescriptors.
+  bool UpdateBuiltInCameraInfo();
+  void UpdateBuiltInCameraInfoOnModuleThread();
+  // Callback for GetNumberOfCameras Mojo IPC function.  GetNumberOfCameras
+  // returns the number of built-in cameras on the device.
+  void OnGotNumberOfCamerasOnModuleThread(int32_t num_cameras);
+  // Callback for SetCallbacks Mojo IPC function. SetCallbacks is called after
+  // GetNumberOfCameras is called for the first time, and before any other calls
+  // to |camera_module_|.
+  void OnSetCallbacksOnModuleThread(int32_t result);
+  void GetCameraInfoOnModuleThread(int32_t camera_id,
+                                   const GetCameraInfoCallback& callback);
+  void OnGotCameraInfoOnModuleThread(int32_t camera_id,
+                                     int32_t result,
+                                     arc::mojom::CameraInfoPtr camera_info);
+
+  // Called by OpenDevice to actually open the device specified by |camera_id|.
+  // This method runs on |module_task_runner_|.
+  void OpenDeviceOnModuleThread(
+      int32_t camera_id,
+      arc::mojom::Camera3DeviceOpsRequest device_ops_request,
+      const OpenDeviceCallback& callback);
+
+  // CameraModuleCallbacks implementation. Operates on |module_task_runner_|.
+  void CameraDeviceStatusChange(
+      int32_t camera_id,
+      arc::mojom::CameraDeviceStatus new_status) final;
+
+  // Signaled when |num_builtin_cameras_| and |camera_info_| are updated.
+  // Queried and waited by UpdateBuiltInCameraInfo, signaled by
+  // OnGotCameraInfoOnModuleThread.
+  base::WaitableEvent builtin_camera_info_updated_;
+
+  // |num_builtin_cameras_| stores the number of built-in camera devices
+  // reported by the camera HAL, and |camera_info_| stores the camera info of
+  // each camera device. They are modified only on |module_task_runner_|. They
+  // are also read in GetSupportedFormats and GetDeviceDescriptors, in which the
+  // access is sequenced through UpdateBuiltInCameraInfo and
+  // |builtin_camera_info_updated_| to avoid race conditions.
+  uint32_t num_builtin_cameras_;
+  std::unordered_map<std::string, arc::mojom::CameraInfoPtr> camera_info_;
+
+  SEQUENCE_CHECKER(sequence_checker_);
+
+  // The task runner where all the camera module Mojo communication takes place.
+  const scoped_refptr<base::SingleThreadTaskRunner> module_task_runner_;
+
+  // The Mojo proxy to access the camera module at the remote camera HAL.  Bound
+  // to |module_task_runner_|.
+  arc::mojom::CameraModulePtr camera_module_;
+
+  // The Mojo binding serving the camera module callbacks.  Bound to
+  // |module_task_runner_|.
+  mojo::Binding<arc::mojom::CameraModuleCallbacks> camera_module_callbacks_;
+
+  DISALLOW_COPY_AND_ASSIGN(CameraHalDelegate);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CAPTURE_VIDEO_CHROMEOS_CAMERA_HAL_DELEGATE_H_