Change ppapi C++ comment style into C.

ppapi/c/ppb_class.h

Index: ppapi/c/ppb_class.h
diff --git a/ppapi/c/ppb_class.h b/ppapi/c/ppb_class.h
index bd0d8efb289be77f2af964f445fad8006d81cb45..ce058c524b43a3b398679d2086258d7ea0464271 100644
--- a/ppapi/c/ppb_class.h
+++ b/ppapi/c/ppb_class.h
@@ -1,7 +1,7 @@
-// Copyright (c) 2010 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.
-
+/* Copyright (c) 2010 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_C_PPB_CLASS_H_
 #define PPAPI_C_PPB_CLASS_H_
 
@@ -121,4 +121,5 @@ struct PPB_Class {
  * @}
  * End addtogroup PPP
  */
-#endif  // PPAPI_C_PPP_CLASS_H_
+#endif  /* PPAPI_C_PPP_CLASS_H_ */
+