Support text track selection in video controls

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 4a9d226cbc8acb1b42e107ee3abf77c4c9e4aa76..3066be78b926f0895167496f3cac5c0bbe74b6de 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -210,6 +210,7 @@ public:
     void textTrackReadyStateChanged(TextTrack*);
 
     void textTrackModeChanged(TextTrack*);
+    void disableAutomaticTextTrackSelection();
 
     // EventTarget function.
     // Both Node (via HTMLElement) and ActiveDOMObject define this method, which
@@ -545,6 +546,7 @@ private:
     bool m_havePreparedToPlay : 1;
     bool m_delayingLoadForPreloadNone : 1;
 
+    bool m_didPerformAutomaticTrackSelection : 1;

[philipj_slow, 2015/05/05 14:36:56]

This name is a bit inaccurate since it can be set to one without actually
performing automatic text track selection. Maybe shouldPerform... would be
better.

However, as I say in another comment, I'm not sure this code is needed at all.

[fs, 2015/05/05 15:32:44]

I believe I suggested this name, with an outset of implementing the flag from
the spec with the same name (only dash-separated of course...) I agree with your
other comment though.

[philipj_slow, 2015/05/06 09:28:43]

Oh, I didn't know about
https://html.spec.whatwg.org/#did-perform-automatic-track-selection or at least
forgot. We should implement that, but in the precise places where the spec says.
With some luck, it might not be needed in this CL at all.

     bool m_tracksAreReady : 1;
     bool m_haveVisibleTextTrack : 1;
     bool m_processingPreferenceChange : 1;