clang/win: Fix most -Wunused-function warnings in Chromium code.

ppapi/tests/test_file_io.cc

 // Copyright (c) 2012 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.
 
 #include "ppapi/tests/test_file_io.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
@@ skipping 109 matching lines @@
       break;
     const std::vector<char>& output = callback.output();
     assert(rv == static_cast<int32_t>(output.size()));
     offset += rv;
     data->append(output.begin(), output.end());
   }
 
   return PP_OK;
 }
 
+#if !defined(PPAPI_OS_WIN)
 bool ReadEntireFileFromFileHandle(int fd, std::string* data) {
   if (lseek(fd, 0, SEEK_SET) < 0)
     return false;
   data->clear();
 
   int ret;
   do {
     char buf[8192];
     ret = read(fd, buf, sizeof(buf));
     if (ret > 0)
       data->append(buf, ret);
   } while (ret > 0);
   return ret == 0;
 }
+#endif  // !defined(PPAPI_OS_WIN)
 
 int32_t WriteEntireBuffer(PP_Instance instance,
                           pp::FileIO* file_io,
                           int32_t offset,
                           const std::string& data,
                           CallbackType callback_type) {
   TestCompletionCallback callback(instance, callback_type);
   int32_t write_offset = offset;
   const char* buf = data.c_str();
   int32_t size = static_cast<int32_t>(data.size());
@@ skipping 1204 matching lines @@
   if ((invalid_combination && callback.result() == PP_OK) ||
       (!invalid_combination &&
        ((callback.result() == PP_OK) != create_if_doesnt_exist))) {
     return ReportOpenError(open_flags);
   }
 
   return std::string();
 }
 
 // TODO(viettrungluu): Test Close(). crbug.com/69457