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

media/capture/video/chromeos/camera_device_context.cc

+// 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.
+
+#include "media/capture/video/chromeos/camera_device_context.h"
+
+namespace media {
+
+CameraDeviceContext::CameraDeviceContext(
+    std::unique_ptr<VideoCaptureDevice::Client> client)
+    : state_(kStopped), rotation_(0), client_(std::move(client)) {
+  DCHECK(client_);
+}
+
+CameraDeviceContext::~CameraDeviceContext() {}
+
+void CameraDeviceContext::SetState(State state) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  state_ = state;
+  if (state_ == kCapturing) {
+    client_->OnStarted();
+  }
+}
+
+CameraDeviceContext::State CameraDeviceContext::GetState() {
+  return state_;
+}
+
+void CameraDeviceContext::SetErrorState(
+    const tracked_objects::Location& from_here,
+    const std::string& reason) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  state_ = kError;
+  LOG(ERROR) << reason;
+  client_->OnError(from_here, reason);
+}
+
+void CameraDeviceContext::LogToClient(std::string message) {
+  client_->OnLog(message);
+}
+
+void CameraDeviceContext::SubmitCapturedData(
+    const uint8_t* data,
+    int length,
+    const VideoCaptureFormat& frame_format,
+    base::TimeTicks reference_time,
+    base::TimeDelta timestamp) {
+  client_->OnIncomingCapturedData(data, length, frame_format, rotation_,

[Pawel Osciak, 2017/06/13 08:40:15]

DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); ?

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

The |sequence_checker_| is mainly for making sure modifications made to |state_|
is serialized. Since client_->OnIncomingCapturedData already allows to be called
on any thread we don't need to do sequence check here.

+                                  reference_time, timestamp);
+}
+
+void CameraDeviceContext::SetRotation(int rotation) {
+  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+  DCHECK(rotation >= 0 && rotation < 360 && rotation % 90 == 0);
+  rotation_ = rotation;
+}
+
+}  // namespace media