VideoCaptureImpl cleanup: merge ctor+Init() and DeInit()+dtor.

content/renderer/media/video_capture_impl.h

Index: content/renderer/media/video_capture_impl.h
diff --git a/content/renderer/media/video_capture_impl.h b/content/renderer/media/video_capture_impl.h
index 74c4d19d33fda6389f867cd4774410b29001c47d..336d5b476d4c5cd776a4bc0dd7c64d7ae64f7637 100644
--- a/content/renderer/media/video_capture_impl.h
+++ b/content/renderer/media/video_capture_impl.h
@@ -48,14 +48,10 @@ class CONTENT_EXPORT VideoCaptureImpl
  public:
   ~VideoCaptureImpl() override;
 
-  VideoCaptureImpl(media::VideoCaptureSessionId session_id,
-                   VideoCaptureMessageFilter* filter);
-
-  // Start listening to IPC messages.
-  void Init();
-
-  // Stop listening to IPC messages.
-  void DeInit();
+  VideoCaptureImpl(
+      media::VideoCaptureSessionId session_id,
+      VideoCaptureMessageFilter* filter,
+      const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner);
 
   // Stop/resume delivering video frames to clients, based on flag |suspend|.
   void SuspendCapture(bool suspend);
@@ -196,7 +192,7 @@ class CONTENT_EXPORT VideoCaptureImpl
   VideoCaptureState state_;
 
   // IO message loop reference for checking correct class operation.
-  scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
+  const scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   // WeakPtrFactory pointing back to |this| object, for use with
   // media::VideoFrames constructed in OnBufferReceived() from buffers cached