Web MIDI: add blink APIs to notify device connection events

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 2baf97676b10a1ae403be44dcd61474e10c1f129..648f290daf11c858cd5f2ef71d529c1b23582975 100644
--- a/Source/modules/webmidi/MIDIAccess.h
+++ b/Source/modules/webmidi/MIDIAccess.h
@@ -77,8 +77,10 @@ public:
     virtual void stop() override;
 
     // 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 didAddInputPort(const String& id, const String& manufacturer, const String& name, const String& version, bool active) override;
+    virtual void didAddOutputPort(const String& id, const String& manufacturer, const String& name, const String& version, bool active) override;
+    virtual void didSetInputPortState(unsigned portIndex, bool active) override;
+    virtual void didSetOutputPortState(unsigned portIndex, bool active) override;
     virtual void didStartSession(bool success, const String& error, const String& message) override
     {
         // This method is for MIDIAccess initialization: MIDIAccessInitializer