Web MIDI: introduce WebMIDIClient API to request a permission

Source/modules/webmidi/MIDIAccess.h

Index: Source/modules/webmidi/MIDIAccess.h
diff --git a/Source/modules/webmidi/MIDIAccess.h b/Source/modules/webmidi/MIDIAccess.h
index 595afceabf03f5a2aa90ec187998a4bdfa0e3877..615e9e4db78ed3853f2dcccfe66b2f337f3fdf0f 100644
--- a/Source/modules/webmidi/MIDIAccess.h
+++ b/Source/modules/webmidi/MIDIAccess.h
@@ -61,6 +61,8 @@ public:
     DEFINE_ATTRIBUTE_EVENT_LISTENER(connect);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(disconnect);
 
+    void enableSysEx(bool enable);
+
     // EventTarget
     virtual const AtomicString& interfaceName() const OVERRIDE { return eventNames().interfaceForMIDIAccess; }
     virtual ScriptExecutionContext* scriptExecutionContext() const OVERRIDE { return ActiveDOMObject::scriptExecutionContext(); }
@@ -72,13 +74,15 @@ public:
     // MIDIAccessorClient
     virtual void didAddInputPort(const String& id, const String& manufacturer, const String& name, const String& version) OVERRIDE;
     virtual void didAddOutputPort(const String& id, const String& manufacturer, const String& name, const String& version) OVERRIDE;
-    virtual void didAllowAccess() OVERRIDE;
-    virtual void didBlockAccess() OVERRIDE;
+    virtual void didStartSession() OVERRIDE;
     virtual void didReceiveMIDIData(unsigned portIndex, const unsigned char* data, size_t length, double timeStamp) OVERRIDE;
 
 private:
     explicit MIDIAccess(ScriptExecutionContext*, MIDIAccessPromise*);
 
+    void startRequest();
+    virtual void permissionDenied();
+
     // EventTarget
     virtual void refEventTarget() OVERRIDE { ref(); }
     virtual void derefEventTarget() OVERRIDE { deref(); }
@@ -92,6 +96,8 @@ private:
 
     OwnPtr<MIDIAccessor> m_accessor;
     bool m_hasAccess;
+    bool m_enableSysEx;
+    bool m_requesting;
 };
 
 } // namespace WebCore