ImageCapture: queue requests if device is not started (Linux,CrOs)

media/capture/video/linux/video_capture_device_linux.h

Index: media/capture/video/linux/video_capture_device_linux.h
diff --git a/media/capture/video/linux/video_capture_device_linux.h b/media/capture/video/linux/video_capture_device_linux.h
index e8adbde8df41715bdd075c0c921c3f6446eb4383..0fcf1cd80792ed8a7c3843eaa1d7278cdfdfbfd0 100644
--- a/media/capture/video/linux/video_capture_device_linux.h
+++ b/media/capture/video/linux/video_capture_device_linux.h
@@ -55,6 +55,9 @@ class VideoCaptureDeviceLinux : public VideoCaptureDevice {
   // VideoCaptureDeviceLinux lives but otherwise operating on |v4l2_thread_|.
   scoped_refptr<V4L2CaptureDelegate> capture_impl_;
 
+  // Photo-related requests waiting for |v4l2_thread_| to be active.
+  std::list<base::Closure> photo_requests_queue_;
+
   base::Thread v4l2_thread_;  // Thread used for reading data from the device.
 
   const VideoCaptureDeviceDescriptor device_descriptor_;