First pass at implementing the MessageLoop interface. This includes a simple

ppapi/thunk/ppb_message_loop_api.h

Index: ppapi/thunk/ppb_message_loop_api.h
diff --git a/ppapi/thunk/ppb_message_loop_api.h b/ppapi/thunk/ppb_message_loop_api.h
new file mode 100644
index 0000000000000000000000000000000000000000..36f2f1a3a0e00d68294b8ba7c65af293344fd33c
--- /dev/null
+++ b/ppapi/thunk/ppb_message_loop_api.h
@@ -0,0 +1,25 @@
+// Copyright (c) 2012 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 PPAPI_THUNK_PPB_MESSAGE_LOOP_API_H_
+#define PPAPI_THUNK_PPB_MESSAGE_LOOP_API_H_
+
+namespace ppapi {
+namespace thunk {
+
+class PPB_MessageLoop_API {
+ public:
+  virtual ~PPB_MessageLoop_API() {}
+
+  virtual int32_t AttachToCurrentThread() = 0;
+  virtual int32_t Run() = 0;
+  virtual int32_t PostWork(PP_CompletionCallback callback,
+                           int64_t delay_ms) = 0;
+  virtual int32_t PostQuit(PP_Bool should_destroy) = 0;
+};
+
+}  // namespace thunk
+}  // namespace ppapi
+
+#endif  // PPAPI_THUNK_PPB_MESSAGE_LOOP_API_H_