Enums recently moved to separate files should still be in the blink namespace.

third_party/WebKit/Source/core/layout/ContentChangeType.h

 // Copyright 2016 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.
 
 #ifndef ContentChangeType_h
 #define ContentChangeType_h
 
+namespace blink {
+
 enum ContentChangeType {
     ImageChanged,
     CanvasChanged,
     CanvasContextChanged
 };
 
+} // namespace blink
+
 #endif // ContentChangeType_h