Support pausing media when a context is frozen.

Media is resumed when the context is unpaused. This feature will be used
for bfcache and pausing iframes feature policy.

BUG=907125

Change-Id: Ic3925ea1a4544242b7bf0b9ad8c9cb9f63976bbd
Reviewed-on: https://chromium-review.googlesource.com/c/1410126
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623319}
void HTMLMediaElement::ConfigureTextTrackDisplay() {
  DCHECK(text_tracks_);
  BLINK_MEDIA_LOG << "configureTextTrackDisplay(" << (void*)this << ")";

  if (processing_preference_change_)
    return;

  bool have_visible_text_track = text_tracks_->HasShowingTracks();
  text_tracks_visible_ = have_visible_text_track;

  if (!have_visible_text_track && !GetMediaControls())
    return;

  GetCueTimeline().UpdateActiveCues(currentTime());

  UpdateTextTrackDisplay();
}

void HTMLMediaElement::ConfigureTextTrackDisplay() {
  DCHECK(text_tracks_);
  BLINK_MEDIA_LOG << "configureTextTrackDisplay(" << (void*)this << ")";

  if (processing_preference_change_)
    return;

  bool have_visible_text_track = text_tracks_->HasShowingTracks();
  text_tracks_visible_ = have_visible_text_track;

  if (!have_visible_text_track && !GetMediaControls())
    return;

  GetCueTimeline().UpdateActiveCues(currentTime());

  UpdateTextTrackDisplay();
}
