Extend |is_type_trait_value| matcher to cover |blink| namespace.

tools/clang/rewrite_to_chrome_style/tests/fields-original.cc

Index: tools/clang/rewrite_to_chrome_style/tests/fields-original.cc
diff --git a/tools/clang/rewrite_to_chrome_style/tests/fields-original.cc b/tools/clang/rewrite_to_chrome_style/tests/fields-original.cc
index 05b75a7a3b7b1b8e81eb0c28b0623fbe294d6e57..52dd12e079f776c7fce795993864c6bff2c31581 100644
--- a/tools/clang/rewrite_to_chrome_style/tests/fields-original.cc
+++ b/tools/clang/rewrite_to_chrome_style/tests/fields-original.cc
@@ -62,6 +62,11 @@ union U {
   int m_hasPrefix;
 };
 
+// https://crbug.com/640749#c1: Some type traits are inside blink namespace.
+struct IsGarbageCollectedMixin {
+  static const bool value = true;
+};
+
 }  // namespace blink
 
 namespace WTF {
@@ -72,7 +77,7 @@ struct TypeTrait1 {
   static const bool value = true;
 };
 
-// Some type traits  are implemented as classes, not structs
+// Some type traits are implemented as classes, not structs
 // (e.g. WTF::IsGarbageCollectedType or WTF::IsAssignable).
 template <typename T>
 class TypeTrait2 {