[MediaStream] Pass request ID parameters in the right order for OpenDevice()

Prior to this CL, requester_id and page_request_id parameters were
passed in incorrect order from MediaStreamDispatcherHost to
MediaStreamManager for the OpenDevice() operation, which could lead to
errors.

Bug: 948564
Change-Id: Iadcf3fe26adaac50564102138ce212269cf32d62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1569113
Reviewed-by: Marina Ciocea <marinaciocea@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#651255}
MediaStreamDispatcherHost::GetMediaStreamDeviceObserver() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  if (media_stream_device_observer_)
    return media_stream_device_observer_;

  blink::mojom::MediaStreamDeviceObserverPtr observer;
  auto dispatcher_request = mojo::MakeRequest(&observer);
  observer.set_connection_error_handler(base::BindOnce(
      &MediaStreamDispatcherHost::OnMediaStreamDeviceObserverConnectionError,
      weak_factory_.GetWeakPtr()));
  base::PostTaskWithTraits(
      FROM_HERE, {BrowserThread::UI},
      base::BindOnce(&BindMediaStreamDeviceObserverRequest, render_process_id_,
                     render_frame_id_, std::move(dispatcher_request)));
  media_stream_device_observer_ = std::move(observer);
  return media_stream_device_observer_;
}

MediaStreamDispatcherHost::GetMediaStreamDeviceObserver() {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  if (media_stream_device_observer_)
    return media_stream_device_observer_;

  blink::mojom::MediaStreamDeviceObserverPtr observer;
  auto dispatcher_request = mojo::MakeRequest(&observer);
  observer.set_connection_error_handler(base::BindOnce(
      &MediaStreamDispatcherHost::OnMediaStreamDeviceObserverConnectionError,
      weak_factory_.GetWeakPtr()));
  base::PostTaskWithTraits(
      FROM_HERE, {BrowserThread::UI},
      base::BindOnce(&BindMediaStreamDeviceObserverRequest, render_process_id_,
                     render_frame_id_, std::move(dispatcher_request)));
  media_stream_device_observer_ = std::move(observer);
  return media_stream_device_observer_;
}
