Enable size_t to int truncation warnings in PPAPI

ppapi/tests/test_file_io.h

 // Copyright (c) 2011 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 PAPPI_TESTS_TEST_FILE_IO_H_
 #define PAPPI_TESTS_TEST_FILE_IO_H_
 
 #include <string>
 
 #include "ppapi/tests/test_case.h"
@@ skipping 39 matching lines @@
   std::string TestRequestOSFileHandleWithOpenExclusive();
   std::string TestMmap();
 
   // Helper method used by TestOpen().
   // |expectations| is a combination of OpenExpectation values. The followings
   // are considered as valid input:
   // 1) INVALID_FLAG_COMBINATION
   // 2) (DONT_)?CREATE_IF_DOESNT_EXIST | (DONT_)?OPEN_IF_EXISTS |
   //    (DONT_)?TRUNCATE_IF_EXISTS
   std::string MatchOpenExpectations(pp::FileSystem* file_system,
-                                    size_t open_flags,
-                                    size_t expectations);
+                                    int32_t open_flags,
+                                    int32_t expectations);
 };
 
 #endif  // PAPPI_TESTS_TEST_FILE_IO_H_