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

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

Index: tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc
diff --git a/tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc b/tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc
index 58c9dc6724525f86ab7ad01bc439b936b47d4a42..a739b7dcb73c217669711b10f9620b13f4e2dd10 100644
--- a/tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc
+++ b/tools/clang/rewrite_to_chrome_style/tests/fields-expected.cc
@@ -65,6 +65,11 @@ union U {
   int has_prefix_;
 };
 
+// https://crbug.com/640749#c1: Some type traits are inside blink namespace.
+struct IsGarbageCollectedMixin {
+  static const bool value = true;
+};
+
 }  // namespace blink
 
 namespace WTF {
@@ -75,7 +80,7 @@ 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 {