Introduce MIDIInputMap and MIDIOutputMap.

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 92a6388bd033fc5fcefdff97c9fbe1858158ce9e..63c4ffd204507756de77e1aef73e496894e96249 100644
--- a/Source/modules/webmidi/MIDIAccess.h
+++ b/Source/modules/webmidi/MIDIAccess.h
@@ -37,14 +37,14 @@
 #include "modules/webmidi/MIDIAccessInitializer.h"
 #include "modules/webmidi/MIDIAccessor.h"
 #include "modules/webmidi/MIDIAccessorClient.h"
-#include "modules/webmidi/MIDIInput.h"
-#include "modules/webmidi/MIDIOutput.h"
 #include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class ExecutionContext;
+class MIDIInputMap;
+class MIDIOutputMap;
 struct MIDIOptions;
 
 class MIDIAccess FINAL : public RefCountedGarbageCollectedWillBeGarbageCollectedFinalized<MIDIAccess>, public ActiveDOMObject, public EventTargetWithInlineData, public MIDIAccessorClient {
@@ -59,8 +59,8 @@ public:
     }
     virtual ~MIDIAccess();
 
-    MIDIInputVector inputs() const { return m_inputs; }
-    MIDIOutputVector outputs() const { return m_outputs; }
+    MIDIInputMap* inputs() const { return m_inputs; }
+    MIDIOutputMap* outputs() const { return m_outputs; }
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(connect);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(disconnect);
@@ -95,8 +95,9 @@ private:
 
     OwnPtr<MIDIAccessor> m_accessor;
     bool m_sysexEnabled;
-    MIDIInputVector m_inputs;
-    MIDIOutputVector m_outputs;
+    Vector<String> m_inputKeys;
+    Member<MIDIInputMap> m_inputs;
+    Member<MIDIOutputMap> m_outputs;
 };
 
 } // namespace blink