Adds Mojo IDL.

third_party/WebKit/Source/bindings/core/v8/custom/V8MojoWatcherCustom.cpp

Index: third_party/WebKit/Source/bindings/core/v8/custom/V8MojoWatcherCustom.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/custom/V8MojoWatcherCustom.cpp b/third_party/WebKit/Source/bindings/core/v8/custom/V8MojoWatcherCustom.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..5fe88912435ea16a6d29014053d7e8b0b8b01463
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/custom/V8MojoWatcherCustom.cpp
@@ -0,0 +1,19 @@
+// Copyright 2016 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.
+
+#include "bindings/core/v8/V8MojoWatcher.h"
+
+#include "bindings/core/v8/MojoWatchCallback.h"
+
+namespace blink {
+
+void V8MojoWatcher::visitDOMWrapperCustom(
+    v8::Isolate* isolate,
+    ScriptWrappable* scriptWrappable,
+    const v8::Persistent<v8::Object>& wrapper) {
+  MojoWatcher* watcher = scriptWrappable->toImpl<MojoWatcher>();
+  watcher->m_callback->setWrapperReference(isolate, wrapper);
+}
+
+}  // namespace blink