Call media query change listeners asynchronously.

Source/core/css/MediaQueryList.h

Index: Source/core/css/MediaQueryList.h
diff --git a/Source/core/css/MediaQueryList.h b/Source/core/css/MediaQueryList.h
index 73beebd28ff5289dc3eedde5af2fb7f117f28cf1..b4b11cbb99f5bd72a6d28abdee5ba8fb2bb12755 100644
--- a/Source/core/css/MediaQueryList.h
+++ b/Source/core/css/MediaQueryList.h
@@ -39,16 +39,35 @@ class MediaQuerySet;
 
 class MediaQueryList FINAL : public RefCountedWillBeGarbageCollectedFinalized<MediaQueryList> {
 public:
+    class Listener : public RefCountedWillBeGarbageCollectedFinalized<Listener> {

[esprehn, 2014/07/01 00:01:06]

This virtual abstraction seems like it could be a separate patch from the timing
change.

[cbiesinger, 2014/07/01 00:12:09]

It could. Want me to do that?

+    public:
+        virtual ~Listener() { }
+        virtual void mediaQueryChanged() = 0;
+        virtual bool equals(Listener* other) { return this == other; }

[esprehn, 2014/07/01 00:01:06]

This shouldn't need to be virtual.

[cbiesinger, 2014/07/01 00:12:09]

How so? The implementation for JS listeners needs to use
ScriptValue::operator==, whereas the C++ implementation needs pointer equality.

+
+        virtual MediaQueryListListener* isMediaQueryListListener() { return nullptr; }
+
+        // Used to keep the MediaQueryList alive and registered with the MediaQueryMatcher
+        // as long as the listener exists.
+        void setMediaQueryList(MediaQueryList* query) { m_query = query; }
+        void clearMediaQueryList() { m_query = nullptr; }
+
+        void trace(Visitor* visitor) { visitor->trace(m_query); }
+    protected:
+        RefPtrWillBeMember<MediaQueryList> m_query;
+    };
+
     static PassRefPtrWillBeRawPtr<MediaQueryList> create(PassRefPtrWillBeRawPtr<MediaQueryMatcher>, PassRefPtrWillBeRawPtr<MediaQuerySet>);
     virtual ~MediaQueryList();
 
     String media() const;
     bool matches();
 
-    void addListener(PassRefPtrWillBeRawPtr<MediaQueryListListener>);
-    void removeListener(PassRefPtrWillBeRawPtr<MediaQueryListListener>);
+    // These listeners will be called at requestAnimationFrame time.
+    void addListener(PassRefPtrWillBeRawPtr<Listener>);
+    void removeListener(PassRefPtrWillBeRawPtr<Listener>);
 
-    void mediaFeaturesChanged(WillBeHeapVector<RefPtrWillBeMember<MediaQueryListListener> >* toNotify);
+    void mediaFeaturesChanged(WillBeHeapVector<RefPtrWillBeMember<Listener> >* listenersToNotify);
 
     void trace(Visitor*);
 
@@ -61,7 +80,7 @@ private:
 
     RefPtrWillBeMember<MediaQueryMatcher> m_matcher;
     RefPtrWillBeMember<MediaQuerySet> m_media;
-    typedef WillBeHeapListHashSet<RefPtrWillBeMember<MediaQueryListListener> > ListenerList;
+    typedef WillBeHeapListHashSet<RefPtrWillBeMember<Listener> > ListenerList;
     ListenerList m_listeners;
     bool m_matchesDirty;
     bool m_matches;