getUserMeida: report device starting states

content/browser/renderer_host/media/video_capture_controller.cc

Index: content/browser/renderer_host/media/video_capture_controller.cc
diff --git a/content/browser/renderer_host/media/video_capture_controller.cc b/content/browser/renderer_host/media/video_capture_controller.cc
index 6d12e40bac04bd0b369c4a3a952206eb0b8efa07..fa67cc871509f61a920c7608d2303dc0096242dd 100644
--- a/content/browser/renderer_host/media/video_capture_controller.cc
+++ b/content/browser/renderer_host/media/video_capture_controller.cc
@@ -471,6 +471,17 @@ void VideoCaptureController::OnLog(const std::string& message) {
   MediaStreamManager::SendMessageToNativeLog("Video capture: " + message);
 }
 
+void VideoCaptureController::OnStarted() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  state_ = VIDEO_CAPTURE_STATE_STARTED;

[chfremer, 2017/02/22 19:13:58]

Why are we setting this here?

Looking at the usages of |state_|, it only ever takes one of two possible
values, VIDEO_CAPTURE_STATE_STARTED and VIDEO_CAPTURE_STATE_ERROR. This means,
what this really is is just a flag indicating whether or not OnError() was
received (I would actually recommend changinge |state_| to a boolean and naming
it |error_flag_| or |is_in_error_state_|). 

Before this CL, it looks like there was not way to change back from
VIDEO_CAPTURE_STATE_ERROR to VIDEO_CAPTURE_STATE_STARTED, and I don't see why we
would intend to change this here. The only way to recover from an error state is
to discard and re-create the device.

[braveyao, 2017/02/23 00:06:25]

Done.
You're right. No need here.

+
+  for (const auto& client : controller_clients_) {
+    if (client->session_closed)
+      continue;
+    client->event_handler->OnStarted(client->controller_id);
+  }
+}
+
 void VideoCaptureController::OnBufferRetired(int buffer_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);