media_controls: Add UI for showing a promo bubble on a control button.

third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h

Index: third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
diff --git a/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h b/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
index 3fc98c34d3e833b79cfc38eb3303adcbed6630f3..7baf7d9c09058086ae429384eee5035eb2546387 100644
--- a/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
+++ b/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
@@ -34,12 +34,14 @@
 namespace blink {
 
 class Event;
+class MediaControlButtonPromoContainer;
 class MediaControlsMediaEventListener;
 class MediaControlsOrientationLockDelegate;
 class MediaControlsRotateToFullscreenDelegate;
 class MediaControlsWindowEventListener;
 class MediaControlCastButtonElement;
 class MediaControlCurrentTimeDisplayElement;
+class MediaControlDownloadButtonContainer;
 class MediaControlDownloadButtonElement;
 class MediaControlFullscreenButtonElement;
 class MediaControlMuteButtonElement;
@@ -210,6 +212,9 @@ class MODULES_EXPORT MediaControlsImpl final : public HTMLDivElement,
   void OnExitedFullscreen();
   void OnPanelKeypress();
 
+  void CreateDownloadButtonPromoUI();
+  void UpdateDownloadButtonWantedState();
+
   // Media control elements.
   Member<MediaControlOverlayEnclosureElement> overlay_enclosure_;
   Member<MediaControlOverlayPlayButtonElement> overlay_play_button_;
@@ -230,7 +235,12 @@ class MODULES_EXPORT MediaControlsImpl final : public HTMLDivElement,
 
   Member<MediaControlCastButtonElement> cast_button_;
   Member<MediaControlFullscreenButtonElement> fullscreen_button_;
+
+  Member<MediaControlDownloadButtonContainer> download_button_container_;
   Member<MediaControlDownloadButtonElement> download_button_;
+  // The promo UI for the download button is lazily created if the UI needs to
+  // be shown.
+  Member<MediaControlButtonPromoContainer> download_promo_container_;
 
   Member<MediaControlsMediaEventListener> media_event_listener_;
   Member<MediaControlsWindowEventListener> window_event_listener_;