Mount MTP devices in Chrome OS Files.app.

chrome/browser/chromeos/fileapi/file_system_backend.h

Index: chrome/browser/chromeos/fileapi/file_system_backend.h
diff --git a/chrome/browser/chromeos/fileapi/file_system_backend.h b/chrome/browser/chromeos/fileapi/file_system_backend.h
index 9578126947160868177a328af31361b54da0e744..3b8b146b9f66f0c7c43489c065f04e71520e954c 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend.h
+++ b/chrome/browser/chromeos/fileapi/file_system_backend.h
@@ -70,6 +70,7 @@ class FileSystemBackend : public fileapi::ExternalFileSystemBackend {
   FileSystemBackend(
       FileSystemBackendDelegate* drive_delegate,
       FileSystemBackendDelegate* file_system_provider_delegate,
+      FileSystemBackendDelegate* mtp_delegate,
       scoped_refptr<quota::SpecialStoragePolicy> special_storage_policy,
       scoped_refptr<fileapi::ExternalMountPoints> mount_points,
       fileapi::ExternalMountPoints* system_mount_points);
@@ -138,6 +139,9 @@ class FileSystemBackend : public fileapi::ExternalFileSystemBackend {
   // The delegate instance for the provided file system related operations.
   scoped_ptr<FileSystemBackendDelegate> file_system_provider_delegate_;
 
+  // The delegate instance for the MTP file system related operations.
+  scoped_ptr<FileSystemBackendDelegate> mtp_delegate_;
+
   // Mount points specific to the owning context (i.e. per-profile mount
   // points).
   //