Introduce MIDIInputMap and MIDIOutputMap.

Source/modules/webmidi/MIDIOutputMap.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MIDIOutputMap_h
+#define MIDIOutputMap_h
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "modules/webmidi/MIDIOutput.h"
+#include "modules/webmidi/MIDIPortMap.h"
+
+namespace blink {
+
+class MIDIOutputMap : public MIDIPortMap<MIDIOutput>, public ScriptWrappable {
+public:
+    MIDIOutputMap(HeapHashMap<String, Member<MIDIOutput> > map)
+        : MIDIPortMap<MIDIOutput>(map) { ScriptWrappable::init(this); }
+
+    ScriptValue getPublic(ScriptState* scriptState, const String& id)
+    {
+        MIDIOutput* result = get(id);
+        if (result)
+            return ScriptValue(scriptState, V8ValueTraits<MIDIOutput*>::toV8Value(result, scriptState->context()->Global(), scriptState->isolate()));

[haraken, 2014/08/29 06:19:42]

Why can't we just call toV8() instead of V8ValueTraits::toV8Value()?

[yhirano, 2014/08/29 07:29:13]

That's because we don't include V8MIDIOutput.h.
I don't quite understand the policy here. Which is more preferable?
 - Include V8MIDIOutput.h and use toV8
 - Do not include V8MIDIOutput.h and use toV8NoInline or
V8ValueTraits::toV8Value

[yhirano, 2014/08/29 07:31:50]

Sorry for the poor English. I meant "Because we don't include...".

[haraken, 2014/08/31 07:18:57]

It's confusing to have multiple ways to convert a native value to a V8 value.
Probably can we replace toV8NoInline with V8ValueTraits::toV8Value? I mean, is
it possible to deprecate toV8NoInline by adopting the following rules?

- Use toV8 if you cannot include V8X.h.
- Use V8ValueTraits::toV8Value if you cannot include V8X.h (this should be rare
cases)

[yhirano, 2014/09/01 02:22:10]

OK, I understand including bindings/{core, modules}/v8/V8*.h is fine. I have a
question (note related to this CL): Can we includes bindings/{core,
modules}/v8/custom/V8*Custom.h as well?
V8ValueTraits::toV8Value uses toV8NoInline, but we could add a "not to use
toV8NoInline" comment.
I added a comment at V8Binding.h. What do you think about it?

[haraken, 2014/09/01 07:17:47]

That's technically possible, but in what cases do you want to do that?
Looks good.

[yhirano, 2014/09/01 07:31:35]

I am reviewing a CL doing it and I want to understand the policy clearly:
https://codereview.chromium.org/516603004/diff/60001/Source/modules/servicewo...

+        return ScriptValue(scriptState, v8::Undefined(scriptState->isolate()));
+    }
+};
+
+} // namespace blink
+
+#endif