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

content/browser/renderer_host/media/in_process_video_capture_device_launcher.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/in_process_video_capture_device_launcher.h"
 
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/stringprintf.h"
 #include "content/browser/media/capture/desktop_capture_device_uma_types.h"
 #include "content/browser/media/capture/web_contents_video_capture_device.h"
@@ skipping 74 matching lines @@
 
   base::Closure start_capture_closure;
   // Use of Unretained |this| is safe, because |done_cb| guarantees that |this|
   // stays alive.
   ReceiveDeviceCallback after_start_capture_callback = media::BindToCurrentLoop(
       base::Bind(&InProcessVideoCaptureDeviceLauncher::OnDeviceStarted,
                  base::Unretained(this), callbacks, base::Passed(&done_cb)));
 
   switch (stream_type) {
     case MEDIA_DEVICE_VIDEO_CAPTURE: {
+      if (!video_capture_system_) {
+        callbacks->OnDeviceLaunchFailed();

[emircan, 2017/05/18 18:40:16]

This becomes the second caller of OnDeviceLaunchFailed(). I think you should add
some logs to explain why it failed to distinguish between failures.

[chfremer, 2017/05/18 19:03:21]

Good point. I realized that this code path is actually expected to never be
reached, so instead of adding the logging, I am proposing to use a NOTREACHED
here.

Done.

+        base::ResetAndReturn(&done_cb).Run();
+        return;
+      }
       start_capture_closure =
           base::Bind(&InProcessVideoCaptureDeviceLauncher::
                          DoStartDeviceCaptureOnDeviceThread,
                      base::Unretained(this), device_id, params,
                      base::Passed(std::move(device_client)),
                      std::move(after_start_capture_callback));
       break;
     }
     case MEDIA_TAB_VIDEO_CAPTURE:
       start_capture_closure = base::Bind(
@@ skipping 53 matching lines @@
     Callbacks* callbacks,
     base::OnceClosure done_cb,
     std::unique_ptr<media::VideoCaptureDevice> device) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   State state_copy = state_;
   state_ = State::READY_TO_LAUNCH;
   if (!device) {
     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();
         return;
     }
   }
 
   auto launched_device = base::MakeUnique<InProcessLaunchedVideoCaptureDevice>(
       std::move(device), device_task_runner_);
 
   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;
   }
-  base::ResetAndReturn(&done_cb).Run();
 }
 
 void InProcessVideoCaptureDeviceLauncher::DoStartDeviceCaptureOnDeviceThread(
     const std::string& device_id,
     const media::VideoCaptureParams& params,
     std::unique_ptr<media::VideoCaptureDeviceClient> device_client,
     ReceiveDeviceCallback result_callback) {
   SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StartDeviceTime");
   DCHECK(device_task_runner_->BelongsToCurrentThread());
+  DCHECK(video_capture_system_);
 
   std::unique_ptr<media::VideoCaptureDevice> video_capture_device =
       video_capture_system_->CreateDevice(device_id);
 
   if (!video_capture_device) {
     result_callback.Run(nullptr);
     return;
   }
 
   video_capture_device->AllocateAndStart(params, std::move(device_client));
@@ skipping 67 matching lines @@
   if (!video_capture_device) {
     result_callback.Run(nullptr);
     return;
   }
 
   video_capture_device->AllocateAndStart(params, std::move(device_client));
   result_callback.Run(std::move(video_capture_device));
 }
 
 }  // namespace content