Adds Mojo IDL.

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

Index: third_party/WebKit/Source/core/mojo/MojoWatcher.h
diff --git a/third_party/WebKit/Source/core/mojo/MojoWatcher.h b/third_party/WebKit/Source/core/mojo/MojoWatcher.h
new file mode 100644
index 0000000000000000000000000000000000000000..5a1c46e72c332fcaae5f6b0ebe8f0d8e4fa75698
--- /dev/null
+++ b/third_party/WebKit/Source/core/mojo/MojoWatcher.h
@@ -0,0 +1,54 @@
+// 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.
+
+#ifndef MojoWatcher_h
+#define MojoWatcher_h
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "mojo/public/cpp/system/handle.h"
+
+namespace blink {
+
+class MojoWatchCallback;
+class ScriptState;
+class WebTaskRunner;
+
+class MojoWatcher final : public GarbageCollectedFinalized<MojoWatcher>,
+                          public ScriptWrappable {
+  DEFINE_WRAPPERTYPEINFO();
+
+ public:
+  static MojoWatcher* create(mojo::Handle,
+                             MojoHandleSignals,
+                             ScriptState*,
+                             MojoWatchCallback*);
+  virtual ~MojoWatcher();
+
+  MojoResult cancel();
+
+  DECLARE_TRACE();
+
+ private:
+  friend class V8MojoWatcher;

[esprehn, 2016/10/25 03:34:06]

Why friends?

[alokp, 2016/10/25 05:01:37]

V8MojoWatcher accesses m_callback to call setWrapperReference. Please see
V8MojoWatcherCustom.cpp. 

+  class RunReadyCallbackTask;
+
+  MojoWatcher(mojo::Handle,
+              ScriptState*,
+              MojoWatchCallback*,
+              std::unique_ptr<WebTaskRunner>);
+  static void onHandleReady(uintptr_t,

[esprehn, 2016/10/25 03:34:07]

add argument names for primitive types

[alokp, 2016/10/25 05:01:37]

Done.

+                            MojoResult,
+                            MojoHandleSignalsState,
+                            MojoWatchNotificationFlags);
+  void runReadyCallback(MojoResult);
+
+  mojo::Handle m_handle;

[esprehn, 2016/10/25 03:34:06]

Hmm, you use mojo::ScopedHandle in Handle, but just mojo::Handle here, why? 

[alokp, 2016/10/25 05:01:37]

Because blink::MojoHandle owns mojo::Handle (closes the handle in destructor).
blink::MojoWatcher just watches the mojo::Handle for certain events.

+  RefPtr<ScriptState> m_scriptState;
+  Member<MojoWatchCallback> m_callback;
+  std::unique_ptr<WebTaskRunner> m_taskRunner;
+};
+
+}  // namespace blink
+
+#endif  // MojoWatcher_h