Follow macro invocations when checking if a violation happened in a .cc file.

tools/clang/plugins/FindBadConstructsAction.cpp

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "FindBadConstructsAction.h"
 
 #include "clang/AST/ASTConsumer.h"
 #include "clang/Frontend/FrontendPluginRegistry.h"
 
 #include "FindBadConstructsConsumer.h"
@@ skipping 44 matching lines @@
       options_.enforce_in_thirdparty_webkit = true;
       options_.enforce_overriding_blink = true;
     } else if (args[i] == "check-enum-last-value") {
       // TODO(tsepez): Enable this by default once http://crbug.com/356815
       // and http://crbug.com/356816 are fixed.
       options_.check_enum_last_value = true;
     } else if (args[i] == "with-ast-visitor") {
       options_.with_ast_visitor = true;
     } else if (args[i] == "check-templates") {
       options_.check_templates = true;
+    } else if (args[i] == "follow-macro-expansion") {
+      options_.follow_macro_expansion = true;
     } else {
       parsed = false;
       llvm::errs() << "Unknown clang plugin argument: " << args[i] << "\n";
     }
   }
 
   return parsed;
 }
 
 }  // namespace chrome_checker
 
 static FrontendPluginRegistry::Add<chrome_checker::FindBadConstructsAction> X(
     "find-bad-constructs",
     "Finds bad C++ constructs");