Add GetURLForBrowserTab method to the external file system backend.

chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc

Index: chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc
diff --git a/chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc b/chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc
index 21de2026f6d8845d07ce65fc85b29cc1701eacf6..dfbe6dc69ac04113de12c123842cfa58e930b7e9 100644
--- a/chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc
+++ b/chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc
@@ -56,4 +56,10 @@ storage::WatcherManager* MTPFileSystemBackendDelegate::GetWatcherManager(
   return NULL;
 }
 
+void MTPFileSystemBackendDelegate::GetURLForBrowserTab(
+    const storage::FileSystemURL& url,
+    const URLCallback& callback) {
+  callback.Run(GURL());

[mtomasz, 2014/09/04 05:30:01]

How about checking for the url.type like in #47? Note, that I don't do that in
#55, because the method is not implemented. However, this method is implemented.
Basically there is never redirection for mtp.

[hirono, 2014/09/04 06:10:59]

Done.

+}
+
 }  // namespace chromeos