Make ExtensionIconSet::ContainsPath use StringPiece.

extensions/common/extension_icon_set.cc

 // 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.
 
 #include "extensions/common/extension_icon_set.h"
 
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 
@@ skipping 35 matching lines @@
          ++iter) {
       if (iter->first >= size) {
         result = iter;
         break;
       }
     }
     return result == map_.end() ? base::EmptyString() : result->second;
   }
 }
 
-bool ExtensionIconSet::ContainsPath(const std::string& path) const {
+bool ExtensionIconSet::ContainsPath(base::StringPiece path) const {
   return GetIconSizeFromPath(path) != 0;
 }
 
-int ExtensionIconSet::GetIconSizeFromPath(const std::string& path) const {
+int ExtensionIconSet::GetIconSizeFromPath(base::StringPiece path) const {
   if (path.empty())
     return 0;
 
   DCHECK_NE(path[0], '/') <<
       "ExtensionIconSet stores icon paths without leading slash.";
 
   for (IconMap::const_iterator iter = map_.begin(); iter != map_.end();
        ++iter) {
     if (iter->second == path)
       return iter->first;
   }
 
   return 0;
 }
 
 void ExtensionIconSet::GetPaths(std::set<base::FilePath>* paths) const {
   CHECK(paths);
   for (auto iter : map())
     paths->insert(base::FilePath::FromUTF8Unsafe(iter.second));
 }