Force another diagnostic reporting path to be warn-only on Windows.

tools/clang/plugins/ChromeClassTester.cpp

Index: tools/clang/plugins/ChromeClassTester.cpp
diff --git a/tools/clang/plugins/ChromeClassTester.cpp b/tools/clang/plugins/ChromeClassTester.cpp
index e9a0bcac479cae3b7d87a100f87a1b5f9c812504..b9d49c3fc8203d7e09e2850e68b1eae6e4025386 100644
--- a/tools/clang/plugins/ChromeClassTester.cpp
+++ b/tools/clang/plugins/ChromeClassTester.cpp
@@ -95,9 +95,13 @@ void ChromeClassTester::emitWarning(SourceLocation loc,
   std::string err;
   err = "[chromium-style] ";
   err += raw_error;
+  // TODO(dcheng): Re-enable -Werror for these diagnostics on Windows once all
+  // the pre-existing warnings are cleaned up. https://crbug.com/467287
   DiagnosticIDs::Level level =
+#if !defined(LLVM_ON_WIN32)
       diagnostic().getWarningsAsErrors() ?
       DiagnosticIDs::Error :
+#endif
       DiagnosticIDs::Warning;
   unsigned id = diagnostic().getDiagnosticIDs()->getCustomDiagID(level, err);
   DiagnosticBuilder builder = diagnostic().Report(full, id);