mediaview: Skeleton for ARC Documents Provider FS.

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 d2a04540e4d1d6ab0c0772ab664495a847ab7b2f..4a796d874db435f23eb9c43f8207cb8a5b2ccaf3 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend.h
+++ b/chrome/browser/chromeos/fileapi/file_system_backend.h
@@ -73,6 +73,8 @@ class FileSystemBackend : public storage::ExternalFileSystemBackend {
       std::unique_ptr<FileSystemBackendDelegate> file_system_provider_delegate,
       std::unique_ptr<FileSystemBackendDelegate> mtp_delegate,
       std::unique_ptr<FileSystemBackendDelegate> arc_content_delegate,
+      std::unique_ptr<FileSystemBackendDelegate>
+          arc_documents_provider_delegate,
       scoped_refptr<storage::ExternalMountPoints> mount_points,
       storage::ExternalMountPoints* system_mount_points);
   ~FileSystemBackend() override;
@@ -155,6 +157,9 @@ class FileSystemBackend : public storage::ExternalFileSystemBackend {
   // The delegate instance for the ARC content file system related operations.
   std::unique_ptr<FileSystemBackendDelegate> arc_content_delegate_;
 
+  // The delegate instance for the ARC documents provider related operations.
+  std::unique_ptr<FileSystemBackendDelegate> arc_documents_provider_delegate_;
+
   // Mount points specific to the owning context (i.e. per-profile mount
   // points).
   //