Change ppapi C++ comment style into C.

ppapi/c/ppb_class.h

-// 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_
 
 #include "ppapi/c/pp_module.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/c/ppb_var.h"
 
 #define PPB_CLASS_INTERFACE "PPB_Class;0.4"
@@ skipping 99 matching lines @@
    */
   struct PP_Var (*Instantiate)(PP_Resource class_object,
                                void* native_ptr,
                                struct PP_Var* exception);
 };
 
 /**
  * @}
  * End addtogroup PPP
  */
-#endif  // PPAPI_C_PPP_CLASS_H_
+#endif  /* PPAPI_C_PPP_CLASS_H_ */
+