Added plumbing for the availablechange event from Blink to WebPresentationClient.

Source/modules/presentation/Presentation.h

Index: Source/modules/presentation/Presentation.h
diff --git a/Source/modules/presentation/Presentation.h b/Source/modules/presentation/Presentation.h
index f075f735defa029934d85005b0dfbde8dcd4e0ec..243bfa2ab2114d761588fe406ba85c4837f90e4f 100644
--- a/Source/modules/presentation/Presentation.h
+++ b/Source/modules/presentation/Presentation.h
@@ -12,6 +12,7 @@
 
 namespace blink {
 
+class PresentationController;
 class ScriptState;
 
 class Presentation final
@@ -37,9 +38,16 @@ public:
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(availablechange);
 
+    virtual bool addEventListener(const AtomicString&, PassRefPtr<EventListener>, bool) override;

[Peter Beverloo, 2015/01/07 14:29:09]

Please give the "AtomicString" and "bool" arguments a name, as it's not obvious
what they mean.

[whywhat, 2015/01/07 16:22:16]

Done.

+    virtual bool removeEventListener(const AtomicString&, PassRefPtr<EventListener>, bool) override;
+
+    void deviceAvailabilityChanged(bool available);
 private:
     explicit Presentation(ExecutionContext*);
 
+    PresentationController* presentationController();
+    LocalFrame* frame();
+
     Member<PresentationSession> m_session;
 };