Clang style plugin: add warn-only option and use it on Windows

tools/clang/plugins/FindBadConstructsConsumer.cpp

Index: tools/clang/plugins/FindBadConstructsConsumer.cpp
diff --git a/tools/clang/plugins/FindBadConstructsConsumer.cpp b/tools/clang/plugins/FindBadConstructsConsumer.cpp
index 20919a41afd7afb98a90211160b36d23cccacac7..4dc305e4a4e3d61bd751ce65f44812348e8335bc 100644
--- a/tools/clang/plugins/FindBadConstructsConsumer.cpp
+++ b/tools/clang/plugins/FindBadConstructsConsumer.cpp
@@ -101,7 +101,7 @@ bool IsPodOrTemplateType(const CXXRecordDecl& record) {
 
 FindBadConstructsConsumer::FindBadConstructsConsumer(CompilerInstance& instance,
                                                      const Options& options)
-    : ChromeClassTester(instance), options_(options) {
+    : ChromeClassTester(instance, options) {
   // Messages for virtual method specifiers.
   diag_method_requires_override_ =
       diagnostic().getCustomDiagID(getErrorLevel(), kMethodRequiresOverride);
@@ -593,19 +593,6 @@ FindBadConstructsConsumer::CheckRecordForRefcountIssue(
   return None;
 }
 
-// Adds either a warning or error, based on the current handling of
-// -Werror.
-DiagnosticsEngine::Level FindBadConstructsConsumer::getErrorLevel() {
-#if defined(LLVM_ON_WIN32)
-  // TODO(dcheng): Re-enable -Werror for these diagnostics on Windows once all
-  // the pre-existing warnings are cleaned up. https://crbug.com/467287
-  return DiagnosticsEngine::Warning;
-#else
-  return diagnostic().getWarningsAsErrors() ? DiagnosticsEngine::Error
-                                            : DiagnosticsEngine::Warning;
-#endif
-}
-
 // Returns true if |base| specifies one of the Chromium reference counted
 // classes (base::RefCounted / base::RefCountedThreadSafe).
 bool FindBadConstructsConsumer::IsRefCountedCallback(