[WIP] make GURL::path() return a StringPiece

extensions/common/file_util.cc

 // Copyright 2013 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/file_util.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 418 matching lines @@
     return base::FilePath();
   }
   return temp_path;
 }
 
 void DeleteFile(const base::FilePath& path, bool recursive) {
   base::DeleteFile(path, recursive);
 }
 
 base::FilePath ExtensionURLToRelativeFilePath(const GURL& url) {
-  std::string url_path = url.path();
+  base::StringPiece url_path = url.path();
   if (url_path.empty() || url_path[0] != '/')
     return base::FilePath();
 
   // Drop the leading slashes and convert %-encoded UTF8 to regular UTF8.
   std::string file_path = net::UnescapeURLComponent(
-      url_path,
+      url_path.as_string(),
       net::UnescapeRule::SPACES |
           net::UnescapeRule::URL_SPECIAL_CHARS_EXCEPT_PATH_SEPARATORS);
   size_t skip = file_path.find_first_not_of("/\\");
   if (skip != file_path.npos)
     file_path = file_path.substr(skip);
 
   base::FilePath path = base::FilePath::FromUTF8Unsafe(file_path);
 
   // It's still possible for someone to construct an annoying URL whose path
   // would still wind up not being considered relative at this point.
@@ skipping 164 matching lines @@
 base::FilePath GetVerifiedContentsPath(const base::FilePath& extension_path) {
   return extension_path.Append(kMetadataFolder)
       .Append(kVerifiedContentsFilename);
 }
 base::FilePath GetComputedHashesPath(const base::FilePath& extension_path) {
   return extension_path.Append(kMetadataFolder).Append(kComputedHashesFilename);
 }
 
 }  // namespace file_util
 }  // namespace extensions