Remove some unnecessary using namespaces and add include guards

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

 // 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.
 
+#ifndef ColumnBalancer_h
+#define ColumnBalancer_h
+
 #include "core/layout/LayoutMultiColumnSet.h"
 
 namespace blink {
 
 // A column balancer traverses a portion of the subtree of a flow thread that
 // belongs to one or more fragmentainer groups within one column set, in order
 // to collect certain data to be used for column balancing. This is an abstract
 // class that just walks the subtree and leaves it to subclasses to actually
 // collect data.
 class ColumnBalancer {
@@ skipping 248 matching lines @@
 
   // Set when breaking before a block, and we're looking for the first
   // unbreakable descendant, in order to report correct space shortage for that
   // one.
   LayoutUnit m_pendingStrut;
 
   unsigned m_forcedBreaksCount;
 };
 
 }  // namespace blink
+
+#endif  // ColumnBalancer_h