Add API definition and error values for running message loops.

ppapi/cpp/dev/message_loop_dev.h

Index: ppapi/cpp/dev/message_loop_dev.h
diff --git a/ppapi/cpp/dev/message_loop_dev.h b/ppapi/cpp/dev/message_loop_dev.h
new file mode 100644
index 0000000000000000000000000000000000000000..b3eb79113c7df3f7782dd2477bf1ca020fe6ba74
--- /dev/null
+++ b/ppapi/cpp/dev/message_loop_dev.h
@@ -0,0 +1,40 @@
+// 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_CPP_DEV_MESSAGE_LOOP_DEV_H_
+#define PPAPI_CPP_DEV_MESSAGE_LOOP_DEV_H_
+
+#include "ppapi/cpp/resource.h"
+
+namespace pp {
+
+class CompletionCallback;
+class Instance;
+
+class MessageLoop_Dev : public Resource {
+ public:
+  // Creates an is_null() MessageLoop resource.
+  MessageLoop_Dev();
+
+  // Creates a message loop associated with the given instance. The resource
+  // will be is_null() on failure.
+  MessageLoop_Dev(Instance* instance);
+
+  // Constructors from an existing resource.
+  MessageLoop_Dev(const MessageLoop_Dev& other);
+  MessageLoop_Dev(PP_Resource pp_message_loop);

[dmichael (off chromium), 2012/01/18 21:16:53]

Is it worth noting that the MessageLoop_Dev takes a reference to the
PP_Resource, which it releases on destruction?

+
+  static MessageLoop_Dev GetForMainThread();
+  static MessageLoop_Dev GetCurrent();
+
+  int32_t AttachToCurrentThread();
+  int32_t Run();
+  int32_t PostWork(const CompletionCallback& callback,
+                   int64_t delay_ms = 0);
+  int32_t PostQuit(bool should_destroy);

[dmichael (off chromium), 2012/01/18 21:16:53]

you should adapt the comments from the C file, once you're happy with those.

+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_DEV_MESSAGE_LOOP_DEV_H_