Ensure that TemplateURLs removed by prepopulate search engine merging is also removed from Sync.

chrome/browser/search_engines/template_url_service.h

Index: chrome/browser/search_engines/template_url_service.h
diff --git a/chrome/browser/search_engines/template_url_service.h b/chrome/browser/search_engines/template_url_service.h
index 87469c271688df6190838fbd74429ba0b47ae7e6..4c50bedcc4e578b473e697f90f555ad495dc518e 100644
--- a/chrome/browser/search_engines/template_url_service.h
+++ b/chrome/browser/search_engines/template_url_service.h
@@ -354,6 +354,8 @@ class TemplateURLService : public WebDataServiceConsumer,
                            FindDuplicateOfSyncTemplateURL);
   FRIEND_TEST_ALL_PREFIXES(TemplateURLServiceSyncTest,
                            MergeSyncAndLocalURLDuplicates);
+  FRIEND_TEST_ALL_PREFIXES(TemplateURLServiceSyncTest,
+                           PreSyncDeletes);
 
   friend class TemplateURLServiceTestUtil;
 
@@ -545,6 +547,9 @@ class TemplateURLService : public WebDataServiceConsumer,
   // where old entries were being pushed to Sync without a sync_guid.
   void PatchMissingSyncGUIDs(TemplateURLVector* template_urls);
 
+  // Adds |guid| to |pre_sync_deletes_|.
+  void AddPreSyncDeletedGUIDForTesting(const std::string& guid);
+
   content::NotificationRegistrar notification_registrar_;
   PrefChangeRegistrar pref_change_registrar_;
 
@@ -628,6 +633,12 @@ class TemplateURLService : public WebDataServiceConsumer,
   // the Synced default when the default search provider becomes unmanaged.
   bool pending_synced_default_search_;
 
+  // A set of sync GUIDs denoting TemplateURLs that have been removed from this
+  // model or the underlying WebDataService prior to MergeDataAndStartSyncing.
+  // This set is used to determine what entries from the server we want to
+  // ignore locally and return a delete command for.
+  std::set<std::string> pre_sync_deletes_;

[Peter Kasting, 2012/05/15 21:28:10]

Is there any way to keep this as a local that's passed in to the Merge function,
as opposed to a member?  Keeping it as state on the class instance itself feels
slightly wrong to me for some reason.

[SteveT, 2012/05/16 13:26:43]

That's a bit difficult. The reason is because the method where this set is used,
MergeDataAndStartSyncing, is 1) a overridden virtual from some sync interface
that we can't change, and 2) is actually called by the Sync internals and not by
us. So that makes it rather hard to get that local from
OnWebDataServiceRequestDone over to MergeDataAndStartSyncing.

I see why you're concerned, since this set is very much so a one-off thing that
is only used (most of the time) around startup. Happy to make this change if you
can come up with some way to get the data into MergeDataAndStartSyncing without
adding new members.

+
   DISALLOW_COPY_AND_ASSIGN(TemplateURLService);
 };