Change ppapi C++ comment style into C.

ppapi/c/ppp.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_PPP_H_
 #define PPAPI_C_PPP_H_
 
 #include "ppapi/c/pp_module.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/c/ppb.h"
 
 #if __GNUC__ >= 4
 #define PP_EXPORT __attribute__ ((visibility("default")))
 #elif defined(_MSC_VER)
 #define PP_EXPORT __declspec(dllexport)
 #endif
 
 /**
  * @file
  * Defines the API ...
  *
  * {PENDING: undefine PP_EXPORT?}
  * @addtogroup PPP
  * @{
  */
 
-// We don't want name mangling for these external functions.  We only need
-// 'extern "C"' if we're compiling with a C++ compiler.
+/* We don't want name mangling for these external functions.  We only need
+ * 'extern "C"' if we're compiling with a C++ compiler.
+ */
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /**
  * Entrypoint for the module.
  *
  * Returns PP_OK on success, any other value on failure. Failure indicates to
  * the browser that this plugin can not be used. In this case, the plugin will
  * be unloaded and ShutdownModule will NOT be called.
  */
 PP_EXPORT int32_t PPP_InitializeModule(PP_Module module,
                                        PPB_GetInterface get_browser_interface);
 
 /** Called before the plugin module is unloaded. */
 PP_EXPORT void PPP_ShutdownModule();
 
 /**
  * Returns an interface pointer for the interface of the given name, or NULL
  * if the interface is not supported. Interface names should be ASCII.
  */
 PP_EXPORT const void* PPP_GetInterface(const char* interface_name);
 
 #ifdef __cplusplus
-}  // extern "C"
+}  /* extern "C" */
 #endif
 
 /**
  * @}
  * End addtogroup PPP
  */
-#endif  // PPAPI_C_PPP_H_
+#endif  /* PPAPI_C_PPP_H_ */
+