Change ppapi C++ comment style into C.

ppapi/c/pp_completion_callback.h

Index: ppapi/c/pp_completion_callback.h
diff --git a/ppapi/c/pp_completion_callback.h b/ppapi/c/pp_completion_callback.h
index 8e148bc59ac25c4ba6e33f6cc223428d5d7e541c..ac9aa3f71ce1aef1d860b57b31167d166ae5477e 100644
--- a/ppapi/c/pp_completion_callback.h
+++ b/ppapi/c/pp_completion_callback.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_PP_COMPLETION_CALLBACK_H_
 #define PPAPI_C_PP_COMPLETION_CALLBACK_H_
 
@@ -40,7 +40,9 @@ struct PP_CompletionCallback {
 PP_INLINE struct PP_CompletionCallback PP_MakeCompletionCallback(
     PP_CompletionCallback_Func func,
     void* user_data) {
-  struct PP_CompletionCallback cc = { func, user_data };
+  struct PP_CompletionCallback cc;
+  cc.func = func;
+  cc.user_data = user_data;
   return cc;
 }
 
@@ -62,4 +64,5 @@ PP_INLINE struct PP_CompletionCallback PP_BlockUntilComplete() {
  * @}
  * End of addtogroup PP
  */
-#endif  // PPAPI_C_PP_COMPLETION_CALLBACK_H_
+#endif  /* PPAPI_C_PP_COMPLETION_CALLBACK_H_ */
+