Change uses of base::JoinString to pass StringPieces where possible.

chrome/common/extensions/command.cc

 // Copyright (c) 2012 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 "chrome/common/extensions/command.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "extensions/common/error_utils.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/manifest_constants.h"
 
 namespace extensions {
 
@@ skipping 235 matching lines @@
     normalize = true;
   } else if (platform == values::kKeybindingPlatformDefault) {
 #if defined(OS_MACOSX)
     normalize = true;
 #endif
   }
 
   if (!normalize)
     return suggestion;
 
-  std::vector<std::string> tokens = base::SplitString(
+  std::vector<base::StringPiece> tokens = base::SplitStringPiece(
       suggestion, "+", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
   for (size_t i = 0; i < tokens.size(); i++) {
     if (tokens[i] == values::kKeyCtrl)
       tokens[i] = values::kKeyCommand;
     else if (tokens[i] == values::kKeyMacCtrl)
       tokens[i] = values::kKeyCtrl;
   }
   return base::JoinString(tokens, "+");
 }
 
@@ skipping 270 matching lines @@
       accelerator_ = accelerator;
       command_name_ = command_name;
       description_ = description;
       global_ = global;
     }
   }
   return true;
 }
 
 }  // namespace extensions