Mock out GetCurrentDir in NaCl.

src/gtest-filepath.cc

@@ -106,7 +106,14 @@ FilePath FilePath::GetCurrentDir() {
   return FilePath(_getcwd(cwd, sizeof(cwd)) == NULL ? "" : cwd);
 #else
   char cwd[GTEST_PATH_MAX_ + 1] = { '\0' };
-  return FilePath(getcwd(cwd, sizeof(cwd)) == NULL ? "" : cwd);
+  char* result = getcwd(cwd, sizeof(cwd));
+# if GTEST_OS_NACL
+  // getcwd will likely fail in NaCl due to the sandbox, so return something
+  // reasonable. The user may have provided a shim implementation for getcwd,
+  // however, so fallback only when failure is detected.
+  return FilePath(result == NULL ? kCurrentDirectoryString : cwd);
+# endif  // GTEST_OS_NACL
+  return FilePath(result == NULL ? "" : cwd);
 #endif  // GTEST_OS_WINDOWS_MOBILE
 }