Notify <picture> elements when a media query (potentially) changes

Source/core/html/HTMLSourceElement.h

Index: Source/core/html/HTMLSourceElement.h
diff --git a/Source/core/html/HTMLSourceElement.h b/Source/core/html/HTMLSourceElement.h
index 339c12a99af11064554671698340eb12d8e6fb4a..30a5b49639db62b04ea1851c5e8485308ee432a0 100644
--- a/Source/core/html/HTMLSourceElement.h
+++ b/Source/core/html/HTMLSourceElement.h
@@ -26,6 +26,7 @@
 #ifndef HTMLSourceElement_h
 #define HTMLSourceElement_h
 
+#include "core/css/MediaQueryListListener.h"
 #include "core/html/HTMLElement.h"
 #include "platform/Timer.h"
 
@@ -36,6 +37,20 @@ typedef EventSender<HTMLSourceElement> SourceEventSender;
 
 class HTMLSourceElement FINAL : public HTMLElement {
 public:
+    class Listener : public MediaQueryListListener {
+    public:
+        explicit Listener(HTMLSourceElement* element) : m_element(element) { }
+        virtual void call() OVERRIDE
+        {
+            if (m_element)
+                m_element->notifyMediaQueryChanged();
+        }
+
+        void clearElement() { m_element = nullptr; }
+    private:
+        HTMLSourceElement* m_element;
+    };
+
     DECLARE_NODE_FACTORY(HTMLSourceElement);
     virtual ~HTMLSourceElement();
 
@@ -48,6 +63,8 @@ public:
 
     void dispatchPendingEvent(SourceEventSender*);
 
+    bool mediaQueryMatches() const;
+
 private:
     explicit HTMLSourceElement(Document&);
 
@@ -55,6 +72,11 @@ private:
     virtual void removedFrom(ContainerNode*) OVERRIDE;
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE;
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
+
+    void notifyMediaQueryChanged();
+
+    RefPtrWillBeRawPtr<MediaQueryList> m_mediaQueryList;
+    RefPtrWillBeRawPtr<Listener> m_listener;
 };
 
 } // namespace WebCore