Move Contains() method to file_utils, stop relying on in extensions_protocol

chrome/browser/extensions/extension_protocol.cc

 // Copyright (c) 2006-2008 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/browser/extensions/extension_protocol.h"
 
 #include "base/string_util.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
 #include "googleurl/src/url_util.h"
 #include "net/base/net_util.h"
@@ skipping 22 matching lines @@
   replacements.SetPathStr(new_path);
   GURL file_url = extension_url.ReplaceComponents(replacements);
   if (!file_url.is_valid())
     return FilePath();
 
   // Convert the result back to a FilePath.
   FilePath ret_val;
   if (!net::FileURLToFilePath(file_url, &ret_val))
     return FilePath();
 
-  if (!file_util::AbsolutePath(&ret_val))
-    return FilePath();
-
   // Double-check that the path we ended up with is actually inside the
-  // extension root.
-  if (!extension_path.Contains(ret_val))
+  // extension root. We can do this with a simple prefix match because:
+  // a) We control the prefix on both sides, and they should match.
+  // b) GURL normalizes things like "../" and "//" before it gets to us.
+  if (ret_val.value().find(extension_path.value() +
+                           FilePath::kSeparators[0]) != 0)
     return FilePath();
 
   return ret_val;
 }
 
 // Factory registered with URLRequest to create URLRequestJobs for extension://
 // URLs.
 static URLRequestJob* CreateExtensionURLRequestJob(URLRequest* request,
                                                    const std::string& scheme) {
   ChromeURLRequestContext* context =
@@ skipping 28 matching lines @@
 void RegisterExtensionProtocols() {
   // Being a standard scheme allows us to resolve relative paths. This is used
   // by extensions, but not by standalone user scripts.
   url_util::AddStandardScheme(kExtensionURLScheme);
 
   URLRequest::RegisterProtocolFactory(kExtensionURLScheme,
                                       &CreateExtensionURLRequestJob);
   URLRequest::RegisterProtocolFactory(kUserScriptURLScheme,
                                       &CreateUserScriptURLRequestJob);
 }