sync: Remove the remaining conflict sets code

chrome/browser/sync/engine/syncer_types.h

Index: chrome/browser/sync/engine/syncer_types.h
diff --git a/chrome/browser/sync/engine/syncer_types.h b/chrome/browser/sync/engine/syncer_types.h
index e4fde71467aee67f013160080d09c025aa73b295..0d422c0f69418078fda049d0b2607b937b8b9571 100644
--- a/chrome/browser/sync/engine/syncer_types.h
+++ b/chrome/browser/sync/engine/syncer_types.h
@@ -30,15 +30,36 @@ enum UpdateAttemptResponse {
   // Update was applied or safely ignored.
   SUCCESS,
 
-  // Conflicts with the local data representation. This can also mean that the
-  // entry doesn't currently make sense if we applied it.
-  CONFLICT,
+  // The conditions described by the following enum values are not mutually
+  // exclusive.  The list has been ordered according to priority in the case of
+  // overlap, with highest priority first.
+  //
+  // For example, in the case where an item had both the IS_UNSYCNED and
+  // IS_UNAPPLIED_UPDATE flags set (CONFLICT_SIMPLE), and a SERVER_PARENT_ID
+  // that, if applied, would cause a directory loop (CONFLICT_HIERARCHY), and
+  // specifics that we can't decrypt right now (CONFLICT_ENCRYPTION), the
+  // UpdateApplicator would return CONFLICT_ENCRYPTION when attempting to
+  // process the item.
+  //
+  // We do not attempt to resolve CONFLICT_HIERARCHY or CONFLICT_ENCRYPTION
+  // items.  We will leave these updates unapplied and wait for the server
+  // to send us newer updates that will resolve the conflict.
 
   // We were unable to decrypt/encrypt this server data. As such, we can't make
   // forward progress on this node, but because the passphrase may not arrive
   // until later we don't want to get the syncer stuck. See UpdateApplicator
   // for how this is handled.
-  CONFLICT_ENCRYPTION
+  CONFLICT_ENCRYPTION,
+
+  // These are some updates that, if applied, would violate the tree's
+  // invariants.  Examples of this include the server adding children to locally
+  // deleted directories and directory moves that would create loops.
+  CONFLICT_HIERARCHY,
+
+  // This indicates that item was modified both remotely (IS_UNAPPLIED_UPDATE)
+  // and locally (IS_UNSYNCED).  We use the ConflictResolver to decide which of
+  // the changes should take priority, or if we can possibly merge the data.
+  CONFLICT_SIMPLE
 };
 
 enum ServerUpdateProcessingResult {
@@ -132,14 +153,6 @@ class SyncEngineEventListener {
   virtual ~SyncEngineEventListener() {}
 };
 
-// This struct is passed between parts of the syncer during the processing of
-// one sync loop. It lives on the stack. We don't expose the number of
-// conflicts during SyncShare as the conflicts may be solved automatically
-// by the conflict resolver.
-typedef std::vector<syncable::Id> ConflictSet;
-
-typedef std::map<syncable::Id, ConflictSet*> IdToConflictSetMap;
-
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_ENGINE_SYNCER_TYPES_H_