Improve accuracy of detecting type trait fields.

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

 // Copyright 2015 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.
 
 namespace blink {
 
 // Note: do not add any copy or move constructors to this class: doing so will
 // break test coverage that we don't clobber the class name by trying to emit
 // replacements for synthesized functions.
 class C {
@@ skipping 51 matching lines @@
   char four_chars[4];
   short two_shorts[2];
   int one_hopefully_four_byte_int;
   int has_prefix_;
 };
 
 }  // namespace blink
 
 namespace WTF {
 
-struct TypeTrait {
-  // WTF has structs for things like type traits, which we don't want to
-  // capitalize.
+// We don't want to capitalize fields in type traits
+// (i.e. no |value| -> |kValue| rename is undesirable below).
+struct TypeTrait1 {
   static const bool value = true;
 };
 
+// Some type traits  are implemented as classes, not structs
+// (e.g. WTF::IsGarbageCollectedType or WTF::IsAssignable).
+template <typename T>
+class TypeTrait2 {
+ public:
+  static const bool value = false;
+};
+template <>
+class TypeTrait2<void> {
+ public:
+  static const bool value = false;
+};
+
 };  // namespace WTF
 
 void F() {
   // Test that references to a static field are correctly rewritten.
   blink::C::instance_count_++;
   // Force instantiation of a copy constructor for blink::C to make sure field
   // initializers for synthesized functions don't cause weird rewrites.
   blink::C c;
   blink::C c2 = c;
 
-  bool b = WTF::TypeTrait::value;
+  bool b1 = WTF::TypeTrait1::value;
+  bool b2 = WTF::TypeTrait2<void>::value;
 }