Reland Queue commands to the Os to start a video device.

content/browser/renderer_host/media/video_capture_host_unittest.cc

Index: content/browser/renderer_host/media/video_capture_host_unittest.cc
diff --git a/content/browser/renderer_host/media/video_capture_host_unittest.cc b/content/browser/renderer_host/media/video_capture_host_unittest.cc
index 6787a385e6ea46b6e1b361559ab4a26e61db4afc..e9d846ae53681c475428ec9d36c9fda4ba27b2a0 100644
--- a/content/browser/renderer_host/media/video_capture_host_unittest.cc
+++ b/content/browser/renderer_host/media/video_capture_host_unittest.cc
@@ -431,6 +431,7 @@ class VideoCaptureHostTest : public testing::Test {
     host_->OnStartCapture(kDeviceId, opened_session_id_, params);
     host_->OnStopCapture(kDeviceId);
     run_loop.RunUntilIdle();
+    WaitForVideoDeviceThread();
   }
 
 #ifdef DUMP_VIDEO
@@ -493,6 +494,16 @@ class VideoCaptureHostTest : public testing::Test {
     base::RunLoop().RunUntilIdle();
   }
 
+  void WaitForVideoDeviceThread() {
+    base::RunLoop run_loop;
+    media_stream_manager_->video_capture_manager()->device_task_runner()
+        ->PostTaskAndReply(
+            FROM_HERE,
+            base::Bind(&base::DoNothing),
+            run_loop.QuitClosure());
+    run_loop.Run();
+  }
+
   scoped_refptr<MockVideoCaptureHost> host_;
 
  private: