Move MediaControlsWindowEventListener to modules/media_controls/.

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 0edf390865931e132d8d537fd0f07335c5c9bb05..bdb57190b8f17b089545859dbcbc388b2fdf1f67 100644
--- a/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
+++ b/third_party/WebKit/Source/modules/media_controls/MediaControlsImpl.h
@@ -87,13 +87,6 @@ class MODULES_EXPORT MediaControlsImpl final : public HTMLDivElement,
   // Return the internal elements, which is used by registering clicking
   // EventHandlers from MediaControlsWindowEventListener.
   MediaControlPanelElement* panelElement() override { return m_panel; }
-  MediaControlTimelineElement* timelineElement() override { return m_timeline; }
-  MediaControlCastButtonElement* castButtonElement() override {
-    return m_castButton;
-  }
-  MediaControlVolumeSliderElement* volumeSliderElement() override {
-    return m_volumeSlider;
-  }
   void beginScrubbing() override;
   void endScrubbing() override;
   void updateCurrentTimeDisplay() override;
@@ -130,7 +123,11 @@ class MODULES_EXPORT MediaControlsImpl final : public HTMLDivElement,
   DECLARE_VIRTUAL_TRACE();
 
  private:
+  // For composition.

[whywhat, 2017/04/07 20:13:59]

nit: what does composition mean here? As in "composition vs inheritance"?
Maybe rather explain what these classes need access to that can't be exposed in
other ways?

[mlamouri (slow - plz ping), 2017/04/09 15:36:41]

I gave more details.

   friend class MediaControlsMediaEventListener;
+  friend class MediaControlsWindowEventListener;
+
+  // For tests.
   friend class MediaControlsOrientationLockDelegateTest;
   friend class MediaControlsImplTest;