Revert of Use external ID to match native model nodes during bookmark association. (patchset #2 id:40001 of https://codereview.chromium.org/904083002/)

Reason for revert:
Looks like it broke a sync_unittest

http://build.chromium.org/p/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/35199

(But maybe it's a flake?)

Original issue's description:
> Use external ID to match native model nodes during bookmark association.
>
> The fix improves matching of nodes in BookmarkModelAssociator in
> situations where there are multiple bookmarks or folders with the
> same titles or URLs.
> This will address one particular scenario leading to bookmark
> duplication (see crbug.com/118105).
>
> 1) In BookmarkModelAssociator::BuildAssociations, when there are
> multiple native model nodes with matching title / URL, a secondary
> match on external ID is used to pick a preferred one; otherwise
> the first matching node is returned.
> The preferred match on external ID should be applicable in most
> situations except when the native model has been rebuilt from scratch.
> Picking a wrong folder during the association process results in
> duplicating the entire subtree within the wrong folder. This issue
> should be addressed now.
> 2) In BookmarkModelAssociator::ApplyDeletesFromSyncJournal the external
> ID match is now the primary criteria for selecting a native model
> node to be deleted. The previous implementation would pick an arbitrary
> native model node based on just the title / URL match anywhere in the
> node hierarchy. That would happen every time after deleting a bookmark
> or folder and recreating it in another place.
> Since external IDs might be reused, there is a secondary match on
> title and URL to ensure that the right node gets deleted. To avoid
> costly O(N*M) algorithm (where N is number of bookmarks and M is
> number of entries in delete journal), the implementation uses a set
> of external IDs to reduce the cost to O(N*logM).
>
> BUG=456228
>
> Committed: https://crrev.com/89fce43a19e7f8b0225a0d750ec3eb3cb0939e3d
> Cr-Commit-Position: refs/heads/master@{#315401}

TBR=zea@chromium.org,stanisc@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=456228

Review URL: https://codereview.chromium.org/906403003

Cr-Commit-Position: refs/heads/master@{#315444}

2 files changed, 0 insertions, 3 deletions

diff --git a/sync/internal_api/delete_journal.cc b/sync/internal_api/delete_journal.cc
index edd10ae..ebeb5a7 100644
--- a/sync/internal_api/delete_journal.cc
+++ b/sync/internal_api/delete_journal.cc
@@ -21,8 +21,6 @@ void DeleteJournal::GetBookmarkDeleteJournals(
       deleted_entries.begin(); i != deleted_entries.end(); ++i) {
     delete_journal_list->push_back(BookmarkDeleteJournal());
     delete_journal_list->back().id = (*i)->ref(syncer::syncable::META_HANDLE);
-    delete_journal_list->back().external_id =
-        (*i)->ref(syncer::syncable::LOCAL_EXTERNAL_ID);
     delete_journal_list->back().is_folder = (*i)->ref(syncer::syncable::IS_DIR);
 
     const sync_pb::EntitySpecifics& specifics = (*i)->ref(
diff --git a/sync/internal_api/public/delete_journal.h b/sync/internal_api/public/delete_journal.h
index ecf84fe..3152b02 100644
--- a/sync/internal_api/public/delete_journal.h
+++ b/sync/internal_api/public/delete_journal.h
@@ -17,7 +17,6 @@ class BaseTransaction;
 
 struct BookmarkDeleteJournal {
   int64 id;   // Metahandle of delete journal entry.
-  int64 external_id;  // Bookmark ID in the native model.
   bool is_folder;
   sync_pb::EntitySpecifics specifics;
 };