Cleanup: Make ExtensionIconSet::Get return a const std::string& rather than a

extensions/common/extension_icon_set.h

 // Copyright 2014 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 EXTENSIONS_COMMON_EXTENSION_ICON_SET_H_
 #define EXTENSIONS_COMMON_EXTENSION_ICON_SET_H_
 
 #include <map>
 #include <string>
 
@@ skipping 19 matching lines @@
 
   // Remove all icons from the set.
   void Clear();
 
   // Add an icon path to the set. If a path for the specified size is already
   // present, it is overwritten.
   void Add(int size, const std::string& path);
 
   // Gets path value of the icon found when searching for |size| using
   // |mathc_type|.
-  std::string Get(int size, MatchType match_type) const;
+  const std::string& Get(int size, MatchType match_type) const;
 
   // Returns true iff the set contains the specified path.
   bool ContainsPath(const std::string& path) const;
 
   // Returns icon size if the set contains the specified path or 0 if not found.
   int GetIconSizeFromPath(const std::string& path) const;
 
  private:
   IconMap map_;
 };
 
 #endif  // EXTENSIONS_COMMON_EXTENSION_ICON_SET_H_