Implements JS bindings for mojo shared buffer.

third_party/WebKit/Source/core/mojo/MojoHandle.h

Index: third_party/WebKit/Source/core/mojo/MojoHandle.h
diff --git a/third_party/WebKit/Source/core/mojo/MojoHandle.h b/third_party/WebKit/Source/core/mojo/MojoHandle.h
index 78fa9138b91b48b5c6a4a888a89e79b86c7a4235..0a88f8fea7cd45e02fc40489e0c66ccb9d102a69 100644
--- a/third_party/WebKit/Source/core/mojo/MojoHandle.h
+++ b/third_party/WebKit/Source/core/mojo/MojoHandle.h
@@ -12,6 +12,7 @@ namespace blink {
 
 class ArrayBufferOrArrayBufferView;
 class MojoHandleSignals;
+class MojoMapBufferResult;
 class MojoReadMessageFlags;
 class MojoReadMessageResult;
 class MojoWatchCallback;
@@ -29,10 +30,15 @@ class MojoHandle final : public GarbageCollectedFinalized<MojoHandle>,
   MojoWatcher* watch(ScriptState*,
                      const MojoHandleSignals&,
                      MojoWatchCallback*);
+
+  // MessagePipe handle.
   MojoResult writeMessage(ArrayBufferOrArrayBufferView&,
                           const HeapVector<Member<MojoHandle>>&);
   void readMessage(const MojoReadMessageFlags&, MojoReadMessageResult&);
 
+  // SharedBuffer handle.
+  void mapBuffer(unsigned offset, unsigned numBytes, MojoMapBufferResult&);
+
   DEFINE_INLINE_TRACE() {}
 
  private: