Cleanup: Add fileapi::GetIsolatedFileSystemRootURIString

chrome/renderer/extensions/file_system_natives.cc

Index: chrome/renderer/extensions/file_system_natives.cc
diff --git a/chrome/renderer/extensions/file_system_natives.cc b/chrome/renderer/extensions/file_system_natives.cc
index 3239c47a33c4a5dcaf84fcd234324744a1ef5664..af20825fb478b5753d2442b422790f8ca59c6d86 100644
--- a/chrome/renderer/extensions/file_system_natives.cc
+++ b/chrome/renderer/extensions/file_system_natives.cc
@@ -35,21 +35,19 @@ static v8::Handle<v8::Value> GetIsolatedFileSystem(
   std::string name(fileapi::GetIsolatedFileSystemName(context_url.GetOrigin(),
                                                       file_system_id));
 
-  std::string root(fileapi::GetFileSystemRootURI(
-          context_url.GetOrigin(),
-          fileapi::kFileSystemTypeIsolated).spec());
-  root.append(file_system_id);
-  root.append("/");
-
   // The optional second argument is the subfolder within the isolated file
   // system at which to root the DOMFileSystem we're returning to the caller.
+  std::string optional_root_name;
   if (args.Length() == 2) {
     DCHECK(args[1]->IsString());
-    name = *v8::String::Utf8Value(args[1]);
-    root.append(name);
-    root.append("/");
+    optional_root_name = *v8::String::Utf8Value(args[1]);
   }
 
+  std::string root(fileapi::GetIsolatedFileSystemRootURIString(
+      context_url.GetOrigin(),
+      file_system_id,
+      optional_root_name));
+
   return webframe->createFileSystem(
       WebKit::WebFileSystem::TypeIsolated,
       WebKit::WebString::fromUTF8(name),