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

ppapi/tests/test_file_io.cc

Index: ppapi/tests/test_file_io.cc
diff --git a/ppapi/tests/test_file_io.cc b/ppapi/tests/test_file_io.cc
index 87839055feb9963692958d0a07062a00bc2d2c94..cf2d226498f5a2b113f22b0e97d8b50cff28ce2d 100644
--- a/ppapi/tests/test_file_io.cc
+++ b/ppapi/tests/test_file_io.cc
@@ -127,6 +127,7 @@ int32_t ReadToArrayEntireFile(PP_Instance instance,
   return PP_OK;
 }
 
+#if !defined(PPAPI_OS_WIN)
 bool ReadEntireFileFromFileHandle(int fd, std::string* data) {
   if (lseek(fd, 0, SEEK_SET) < 0)
     return false;
@@ -141,6 +142,7 @@ bool ReadEntireFileFromFileHandle(int fd, std::string* data) {
   } while (ret > 0);
   return ret == 0;
 }
+#endif  // !defined(PPAPI_OS_WIN)
 
 int32_t WriteEntireBuffer(PP_Instance instance,
                           pp::FileIO* file_io,