[Mojo Video Capture] Hook up video capture service behind a feature flag

content/browser/renderer_host/media/video_capture_provider_switcher.cc

+// Copyright 2016 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 "content/browser/renderer_host/media/video_capture_provider_switcher.h"
+
+namespace content {
+
+VideoCaptureProviderSwitcher::VideoCaptureProviderSwitcher(
+    std::unique_ptr<VideoCaptureProvider> media_device_capture_provider,
+    std::unique_ptr<VideoCaptureProvider> other_types_capture_provider)
+    : media_device_capture_provider_(std::move(media_device_capture_provider)),
+      other_types_capture_provider_(std::move(other_types_capture_provider)) {}
+
+VideoCaptureProviderSwitcher::~VideoCaptureProviderSwitcher() = default;
+
+void VideoCaptureProviderSwitcher::Uninitialize() {
+  media_device_capture_provider_->Uninitialize();
+  other_types_capture_provider_->Uninitialize();
+}
+
+void VideoCaptureProviderSwitcher::GetDeviceInfosAsync(
+    const base::Callback<void(
+        const std::vector<media::VideoCaptureDeviceInfo>&)>& result_callback) {
+  media_device_capture_provider_->GetDeviceInfosAsync(result_callback);
+}
+
+std::unique_ptr<VideoCaptureDeviceLauncher>
+VideoCaptureProviderSwitcher::CreateDeviceLauncher() {
+  return base::MakeUnique<VideoCaptureDeviceLauncherSwitcher>(
+      media_device_capture_provider_->CreateDeviceLauncher(),
+      other_types_capture_provider_->CreateDeviceLauncher());
+}
+
+VideoCaptureDeviceLauncherSwitcher::VideoCaptureDeviceLauncherSwitcher(
+    std::unique_ptr<VideoCaptureDeviceLauncher> media_device_launcher,
+    std::unique_ptr<VideoCaptureDeviceLauncher> other_types_launcher)
+    : media_device_launcher_(std::move(media_device_launcher)),
+      other_types_launcher_(std::move(other_types_launcher)) {}
+
+VideoCaptureDeviceLauncherSwitcher::~VideoCaptureDeviceLauncherSwitcher() =
+    default;
+
+void VideoCaptureDeviceLauncherSwitcher::LaunchDeviceAsync(
+    const std::string& device_id,
+    MediaStreamType stream_type,
+    const media::VideoCaptureParams& params,
+    base::WeakPtr<media::VideoFrameReceiver> receiver,
+    Callbacks* callbacks,
+    base::OnceClosure done_cb) {
+  last_launched_stream_type_ = stream_type;
+  if (stream_type == content::MEDIA_DEVICE_VIDEO_CAPTURE) {
+    return media_device_launcher_->LaunchDeviceAsync(
+        device_id, stream_type, params, std::move(receiver), callbacks,
+        std::move(done_cb));
+  } else {

[mcasas, 2017/05/10 02:33:33]

No need for else after a return.
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md...

[chfremer, 2017/05/10 17:59:39]

Done.

+    return other_types_launcher_->LaunchDeviceAsync(
+        device_id, stream_type, params, std::move(receiver), callbacks,
+        std::move(done_cb));
+  }
+}
+
+void VideoCaptureDeviceLauncherSwitcher::AbortLaunch() {
+  if (!last_launched_stream_type_.has_value())
+    return;
+  if (last_launched_stream_type_.value() ==
+      content::MEDIA_DEVICE_VIDEO_CAPTURE) {
+    media_device_launcher_->AbortLaunch();
+  } else {
+    other_types_launcher_->AbortLaunch();
+  }

[mcasas, 2017/05/10 02:33:33]

Instead of |last_launched_stream_type_|, bind a member 
callback in LaunchDeviceAsync() to AbortLaunch() and, if 
such Callback is initialized (!callback.is_null()), you call it here.

[chfremer, 2017/05/10 17:59:39]

Done.

+}
+
+}  // namespace content