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

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 5818cef620e58357d7f789e52d61c7e64d4cb19e..9c52d6975899ad49737cc729eeadd9808e2018bf 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -33,7 +33,9 @@
 #include "content/browser/renderer_host/media/media_devices_manager.h"
 #include "content/browser/renderer_host/media/media_stream_requester.h"
 #include "content/browser/renderer_host/media/media_stream_ui_proxy.h"
+#include "content/browser/renderer_host/media/service_video_capture_provider.h"
 #include "content/browser/renderer_host/media/video_capture_manager.h"
+#include "content/browser/renderer_host/media/video_capture_provider_switcher.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
@@ -52,6 +54,7 @@
 #include "media/base/media_switches.h"
 #include "media/capture/video/video_capture_device_factory.h"
 #include "media/capture/video/video_capture_system_impl.h"
+#include "services/video_capture/public/cpp/constants.h"
 #include "url/gurl.h"
 #include "url/origin.h"
 
@@ -423,6 +426,12 @@ MediaStreamManager::MediaStreamManager(
             media::VideoCaptureDeviceFactory::CreateFactory(
                 BrowserThread::GetTaskRunnerForThread(BrowserThread::UI))),
         std::move(device_task_runner));

[mcasas, 2017/05/12 22:07:02]

|device_task_runner| is unused if 
base::FeatureList::IsEnabled(video_capture::kMojoVideoCapture),
and also a |video_capture_provider| is constructed in l.424 and
then discarded in l.431.  Please refactor the block in l.414-434.

[chfremer, 2017/05/12 23:30:21]

Excellent point. Thanks for raising this.
Unfortunately this will require changes outside this block, because right now,
we still need the InProcessVideoCaptureProvider instance for the non-device
capture cases. We will probably have to add a new class
InProcessNonDeviceVideoCaptureProvider, which will not require a
device_task_runner. Should we defer this to a follow-up CL or do it as a
PatchSet here?

[mcasas, 2017/05/12 23:33:01]

Follow up CL is fine.

+    if (base::FeatureList::IsEnabled(video_capture::kMojoVideoCapture)) {
+      DVLOG(3) << "Mojo video capture enabled";

[mcasas, 2017/05/12 22:07:02]

nit: remove this.

[chfremer, 2017/05/12 23:30:21]

Done.

+      video_capture_provider = base::MakeUnique<VideoCaptureProviderSwitcher>(
+          base::MakeUnique<ServiceVideoCaptureProvider>(),
+          std::move(video_capture_provider));
+    }
   }
   InitializeMaybeAsync(std::move(video_capture_provider));