PPAPI: Implement PPB_FileMapping on POSIX

ppapi/api/ppb_file_mapping.idl

 /* Copyright 2014 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.
  */
 
 
 /**
  * This file defines methods for mapping and unmapping files into and out of
  * memory.
  */
 
+[generate_thunk]
+
 label Chrome {
   [channel=dev] M34 = 0.1
 };
 
 /**
  * The PP_FileMapProtection values indicate the permissions requested for the
  * file mapping. These should be used in a uint32_t bitfield.
  */
 [assert_size(4)]
 enum PP_FileMapProtection {
@@ skipping 98 matching lines @@
    * GetMapPageSize() retrieves the size of pages that Map() uses.
    *
    * @param[in] instance A <code>PP_Instance</code> identifying the instance.
    *
    * @return The size of pages that Map() uses. Returns 0 on failure.
    */
   [on_failure=0]
   int64_t GetMapPageSize(PP_Instance instance);
 };