Use ExtractDrivePath(path()) instead of virtual_path() for getting Drive path.

chrome/browser/chromeos/drive/drive_file_system_proxy.cc

Index: chrome/browser/chromeos/drive/drive_file_system_proxy.cc
diff --git a/chrome/browser/chromeos/drive/drive_file_system_proxy.cc b/chrome/browser/chromeos/drive/drive_file_system_proxy.cc
index 282315f1c50c6eb09ca46f044494d2abdba8eb73..63dd419bb5a65ae205d445270a02149a77219db3 100644
--- a/chrome/browser/chromeos/drive/drive_file_system_proxy.cc
+++ b/chrome/browser/chromeos/drive/drive_file_system_proxy.cc
@@ -692,17 +692,7 @@ DriveFileSystemProxy::~DriveFileSystemProxy() {
 // static.
 bool DriveFileSystemProxy::ValidateUrl(
     const FileSystemURL& url, base::FilePath* file_path) {
-  // what platform you're on.
-  if (!url.is_valid() || url.type() != fileapi::kFileSystemTypeDrive)
-    return false;
-
-  // |url.virtual_path()| cannot be used directly because in the case the url is
-  // isolated file system url, the virtual path will be formatted as
-  // <isolated_file_system_id>/<file_name> and thus unusable by drive file
-  // system.
-  // TODO(kinaba): fix other uses of virtual_path() as in
-  // https://codereview.chromium.org/12483010/
-  *file_path = util::ExtractDrivePath(url.path());
+  *file_path = util::ExtractDrivePathFromFileSystemUrl(url);
   return !file_path->empty();
 }