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

ui/base/webui/web_ui_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 "ui/base/webui/web_ui_util.h"
 
 #include <vector>
 
 #include "base/base64.h"
 #include "base/i18n/rtl.h"
@@ skipping 74 matching lines @@
     return false;
   }
   *scale_factor = static_cast<float>(scale);
   return true;
 }
 
 void ParsePathAndScale(const GURL& url,
                        std::string* path,
                        float* scale_factor) {
   *path = net::UnescapeURLComponent(
-      url.path().substr(1),
+      url.path().substr(1).as_string(),
       net::UnescapeRule::URL_SPECIAL_CHARS_EXCEPT_PATH_SEPARATORS |
           net::UnescapeRule::SPACES);
   if (scale_factor)
     *scale_factor = 1.0f;
 
   // Detect and parse resource string ending in @<scale>x.
   std::size_t pos = path->rfind('@');
   if (pos != std::string::npos) {
     base::StringPiece stripped_path(*path);
     float factor;
@@ skipping 70 matching lines @@
           IDS_WEB_FONT_SIZE_XP :
 #endif
           IDS_WEB_FONT_SIZE);
 }
 
 std::string GetTextDirection() {
   return base::i18n::IsRTL() ? "rtl" : "ltr";
 }
 
 }  // namespace webui