[SyncFS] Add MetadataDatabase::UpdateTracker

chrome/browser/sync_file_system/drive_backend/metadata_database.proto

Index: chrome/browser/sync_file_system/drive_backend/metadata_database.proto
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.proto b/chrome/browser/sync_file_system/drive_backend/metadata_database.proto
index 7ef465bb60e7a308685d88aa03082c634cd1e422..d62bc6e260e73045fc276223a8426fee6b33de42 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.proto
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.proto
@@ -18,6 +18,10 @@ enum FileKind {
 
 enum TrackerKind {
   TRACKER_KIND_REGULAR = 0;
+
+  // TODO(tzik): Add TRACKER_KIND_DISABLED_REGULAR and keep all descendants of
+  // disabled app-root disabled.  Disabled trackers should be excluded from
+  // dirty_trackers_ and the sync-engine should not update them.
   TRACKER_KIND_APP_ROOT = 1;
   TRACKER_KIND_DISABLED_APP_ROOT = 2;
 }
@@ -82,4 +86,8 @@ message FileTracker {
   // Valid only for folders.
   // True if the folder contents have not yet been fetched.
   optional bool needs_folder_listing = 9;
+
+  // True when the tracker has both remote change and local change.
+  // SyncEngine should process this change after all local change was processed.
+  optional bool priority_low = 10;

[kinuko, 2013/08/27 13:20:19]

Not used in this CL yet?

This name usually does not imply what the comment says.  If this flag is used
solely for the commented purpose should we rename the flag?  Or if it could be
used just to indicate it should be processed at later stages should the comment
be updated..?

[tzik, 2013/08/30 05:51:57]

Reverted.
It's just a merge failure in my local repo.

 }