PPAPI: Force async callback invocation option.

ppapi/thunk/common.cc

Index: ppapi/thunk/common.cc
===================================================================
--- ppapi/thunk/common.cc	(revision 0)
+++ ppapi/thunk/common.cc	(revision 0)
@@ -0,0 +1,30 @@
+// Copyright (c) 2011 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 "ppapi/thunk/common.h"
+
+#include "base/message_loop.h"
+#include "ppapi/c/pp_errors.h"
+
+namespace ppapi {
+namespace thunk {
+
+int32_t MayForceCallback(PP_CompletionCallback callback, int32_t result) {
+  if (result == PP_OK_COMPLETIONPENDING)
+    return result;
+
+  if (callback.func == NULL ||
+      (callback.flags & PP_COMPLETIONCALLBACK_FLAG_OPTIONAL) != 0)
+    return result;
+
+  // TODO(polina): make this work off the main thread as well
+  // (At this point this should not be an issue because PPAPI is only supported
+  // on the main thread).
+  MessageLoop::current()->PostTask(FROM_HERE, NewRunnableFunction(
+      callback.func, callback.user_data, result));
+  return PP_OK_COMPLETIONPENDING;
+}
+
+}  // namespace thunk
+}  // namespace ppapi