[Mojo Video Capture] Implement a VideoCaptureProvider using the Mojo service (part 1)

content/browser/renderer_host/media/service_video_capture_provider.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 "content/browser/renderer_host/media/service_video_capture_provider.h"
+
+#include "content/browser/renderer_host/media/service_video_capture_device_launcher.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/common/service_manager_connection.h"
+#include "services/service_manager/public/cpp/connector.h"
+#include "services/video_capture/public/interfaces/constants.mojom.h"
+
+namespace content {
+
+ServiceVideoCaptureProvider::ServiceVideoCaptureProvider() {
+  thread_checker_.DetachFromThread();
+  DCHECK(BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  connector_ =
+      ServiceManagerConnection::GetForProcess()->GetConnector()->Clone();
+}
+
+ServiceVideoCaptureProvider::~ServiceVideoCaptureProvider() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void ServiceVideoCaptureProvider::Uninitialize() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  device_factory_.reset();
+  device_factory_provider_.reset();
+}
+
+void ServiceVideoCaptureProvider::GetDeviceInfosAsync(
+    const base::Callback<void(
+        const std::vector<media::VideoCaptureDeviceInfo>&)>& result_callback) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  LazyConnectToService();
+  device_factory_->GetDeviceInfos(result_callback);
+}
+
+std::unique_ptr<VideoCaptureDeviceLauncher>
+ServiceVideoCaptureProvider::CreateDeviceLauncher() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  LazyConnectToService();
+  return base::MakeUnique<ServiceVideoCaptureDeviceLauncher>(&device_factory_);
+}
+
+void ServiceVideoCaptureProvider::LazyConnectToService() {
+  if (device_factory_provider_.is_bound())
+    return;
+
+  connector_->BindInterface(video_capture::mojom::kServiceName,
+                            &device_factory_provider_);
+  device_factory_provider_->ConnectToDeviceFactory(
+      mojo::MakeRequest(&device_factory_));
+  // Unretained |this| is safe, because |this| owns |device_factory_|.
+  device_factory_.set_connection_error_handler(
+      base::Bind(&ServiceVideoCaptureProvider::OnLostConnectionToDeviceFactory,
+                 base::Unretained(this)));
+}
+
+void ServiceVideoCaptureProvider::OnLostConnectionToDeviceFactory() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  // This may indicate that the video capture service has crashed. Uninitialize
+  // here, so that a new connection will be established when clients try to
+  // reconnect.
+  Uninitialize();
+}
+
+}  // namespace content