[Mojo Video Capture] Do not instantiate in-process VideoCaptureSystem when using service

content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc

Index: content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc
diff --git a/content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc b/content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc
index f34de98ff20cb09a577c667e02273e03c2356080..449ed097eacc153117f0d453ffc23c565d777575 100644
--- a/content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc
+++ b/content/browser/renderer_host/media/in_process_video_capture_device_launcher.cc
@@ -57,9 +57,9 @@ namespace content {
 
 InProcessVideoCaptureDeviceLauncher::InProcessVideoCaptureDeviceLauncher(
     scoped_refptr<base::SingleThreadTaskRunner> device_task_runner,
-    media::VideoCaptureSystem* video_capture_system)
+    media::VideoCaptureSystem* optional_video_capture_system)
     : device_task_runner_(std::move(device_task_runner)),
-      video_capture_system_(video_capture_system),
+      optional_video_capture_system_(optional_video_capture_system),
       state_(State::READY_TO_LAUNCH) {}
 
 InProcessVideoCaptureDeviceLauncher::~InProcessVideoCaptureDeviceLauncher() {
@@ -92,6 +92,11 @@ void InProcessVideoCaptureDeviceLauncher::LaunchDeviceAsync(
 
   switch (stream_type) {
     case MEDIA_DEVICE_VIDEO_CAPTURE: {
+      if (!optional_video_capture_system_) {
+        callbacks->OnDeviceLaunchFailed();
+        base::ResetAndReturn(&done_cb).Run();
+        return;
+      }
       start_capture_closure =
           base::Bind(&InProcessVideoCaptureDeviceLauncher::
                          DoStartDeviceCaptureOnDeviceThread,
@@ -165,9 +170,11 @@ void InProcessVideoCaptureDeviceLauncher::OnDeviceStarted(
     switch (state_copy) {
       case State::DEVICE_START_IN_PROGRESS:
         callbacks->OnDeviceLaunchFailed();
+        base::ResetAndReturn(&done_cb).Run();
         return;
       case State::DEVICE_START_ABORTING:
         callbacks->OnDeviceLaunchAborted();
+        base::ResetAndReturn(&done_cb).Run();
         return;
       case State::READY_TO_LAUNCH:
         NOTREACHED();
@@ -181,16 +188,17 @@ void InProcessVideoCaptureDeviceLauncher::OnDeviceStarted(
   switch (state_copy) {
     case State::DEVICE_START_IN_PROGRESS:
       callbacks->OnDeviceLaunched(std::move(launched_device));
+      base::ResetAndReturn(&done_cb).Run();
       return;
     case State::DEVICE_START_ABORTING:
       launched_device.reset();
       callbacks->OnDeviceLaunchAborted();
+      base::ResetAndReturn(&done_cb).Run();
       return;
     case State::READY_TO_LAUNCH:
       NOTREACHED();
       return;
   }

[mcasas, 2017/05/16 22:22:22]

If we want to run |done_cb| in every possible return path,
consider adding in l.167-ish

base::ScopedClosureRunner scoped_callback(done_cb);

which will call Run() on destruction.

[chfremer, 2017/05/16 22:45:02]

Agreed that this would be better and cleaner. Unfortunately it looks like
ScopedClosureRunner does not (yet) support move-only types like OnceClosure.

-  base::ResetAndReturn(&done_cb).Run();
 }
 
 void InProcessVideoCaptureDeviceLauncher::DoStartDeviceCaptureOnDeviceThread(
@@ -202,7 +210,7 @@ void InProcessVideoCaptureDeviceLauncher::DoStartDeviceCaptureOnDeviceThread(
   DCHECK(device_task_runner_->BelongsToCurrentThread());
 
   std::unique_ptr<media::VideoCaptureDevice> video_capture_device =
-      video_capture_system_->CreateDevice(device_id);
+      optional_video_capture_system_->CreateDevice(device_id);

[mcasas, 2017/05/16 22:22:22]

If it's optional, we should check if (optional_video_capture_system_),
right?

[chfremer, 2017/05/16 22:45:01]

True. There is already a check in LaunchDeviceAsync() that should make it so
that this method here never gets called when |optional_video_capture_system_| is
nullptr. I'll add a DCHECK here to make sure.

 
   if (!video_capture_device) {
     result_callback.Run(nullptr);