Fix MediaObserver notifications in MediaStreamManager.

This CL fixes the stream type used to notify MediaObserver about
cancelled MediaStream requests.

Before this CL, NUM_MEDIA_TYPES was used as stream type to indicate
that all stream types should be cancelled.
However, the MediaObserver end does not interpret NUM_MEDIA_TYPES this
way and the request to update the UI is ignored.

This CL sends a separate notification for each stream type so that the
UI actually gets updated for all stream types in use.

Bug: 816033
Change-Id: Ib7d3b3046d1dd0976627f8ab38abf086eacc9405
Reviewed-on: https://chromium-review.googlesource.com/939630
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540122}
void MediaStreamManager::ReadOutputParamsAndPostRequestToUI(
    const std::string& label,
    DeviceRequest* request,
    const MediaDeviceEnumeration& enumeration) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  if (request->audio_type() == MEDIA_TAB_AUDIO_CAPTURE) {
    audio_system_->GetOutputStreamParameters(
        media::AudioDeviceDescription::kDefaultDeviceId,
        base::BindOnce(&MediaStreamManager::PostRequestToUI,
                       base::Unretained(this), label, request, enumeration));
  } else {
    PostRequestToUI(label, request, enumeration,
                    base::Optional<media::AudioParameters>());
  }
}

void MediaStreamManager::ReadOutputParamsAndPostRequestToUI(
    const std::string& label,
    DeviceRequest* request,
    const MediaDeviceEnumeration& enumeration) {
  DCHECK_CURRENTLY_ON(BrowserThread::IO);

  if (request->audio_type() == MEDIA_TAB_AUDIO_CAPTURE) {
    audio_system_->GetOutputStreamParameters(
        media::AudioDeviceDescription::kDefaultDeviceId,
        base::BindOnce(&MediaStreamManager::PostRequestToUI,
                       base::Unretained(this), label, request, enumeration));
  } else {
    PostRequestToUI(label, request, enumeration,
                    base::Optional<media::AudioParameters>());
  }
}
