Update the clang plugin to optionally enforce rules for Blink code.

tools/clang/plugins/Options.h

Index: tools/clang/plugins/Options.h
diff --git a/tools/clang/plugins/Options.h b/tools/clang/plugins/Options.h
index a79bb1e2489b70ec8c84c13753a0d879b1b0dd77..a94c95e85531f94668d87b908497ad95355c914c 100644
--- a/tools/clang/plugins/Options.h
+++ b/tools/clang/plugins/Options.h
@@ -10,14 +10,16 @@ namespace chrome_checker {
 struct Options {
   Options()
       : check_base_classes(false),
-        enforce_blink(false),
+        enforce_overriding_blink(false),
+        enforce_in_thirdparty_webkit(false),
         check_enum_last_value(false),
         with_ast_visitor(false),
         check_templates(false),
         warn_only(false) {}
 
   bool check_base_classes;
-  bool enforce_blink;
+  bool enforce_overriding_blink;  // Blink base-class use
+  bool enforce_in_thirdparty_webkit;  // Use in Blink code itself
   bool check_enum_last_value;
   bool with_ast_visitor;
   bool check_templates;