Revert 164565 - sync: make scheduling logic and job ownership more obvious.

sync/sessions/sync_session.h

Index: sync/sessions/sync_session.h
===================================================================
--- sync/sessions/sync_session.h	(revision 164641)
+++ sync/sessions/sync_session.h	(working copy)
@@ -112,12 +112,26 @@
   // engine again.
   bool HasMoreToSync() const;
 
-  // Returns true if we reached the server. Note that "reaching the server"
-  // here means that from an HTTP perspective, we succeeded (HTTP 200).  The
-  // server **MAY** have returned a sync protocol error.
-  // See SERVER_RETURN_* in the SyncerError enum for values.
-  bool DidReachServer() const;
+  // Returns true if we completely ran the session without errors.
+  //
+  // There are many errors that could prevent a sync cycle from succeeding.
+  // These include invalid local state, inability to contact the server,
+  // inability to authenticate with the server, and server errors.  What they
+  // have in common is that the we either need to take some action and then
+  // retry the sync cycle or, in the case of transient errors, retry after some
+  // backoff timer has expired.  Most importantly, the SyncScheduler should not
+  // assume that the original action that triggered the sync cycle (ie. a nudge
+  // or a notification) has been properly serviced.
+  //
+  // This function also returns false if SyncShare has not been called on this
+  // session yet, or if ResetTransientState() has been called on this session
+  // since the last call to SyncShare.
+  bool Succeeded() const;
 
+  // Returns true if we reached the server successfully and the server did not
+  // return any error codes. Returns false if no connection was attempted.
+  bool SuccessfullyReachedServer() const;
+
   // Collects all state pertaining to how and why |s| originated and unions it
   // with corresponding state in |this|, leaving |s| unchanged.  Allows |this|
   // to take on the responsibilities |s| had (e.g. certain data types) in the
@@ -125,13 +139,11 @@
   // sessions.
   void Coalesce(const SyncSession& session);
 
-  // Compares the routing_info_, workers and payload map with those passed in.
-  // Purges types from the above 3 which are not present in latest. Useful
+  // Compares the routing_info_, workers and payload map with the passed in
+  // session. Purges types from the above 3 which are not in session. Useful
   // to update the sync session when the user has disabled some types from
   // syncing.
-  void RebaseRoutingInfoWithLatest(
-      const ModelSafeRoutingInfo& routing_info,
-      const std::vector<ModelSafeWorker*>& workers);
+  void RebaseRoutingInfoWithLatest(const SyncSession& session);
 
   // Should be called any time |this| is being re-used in a new call to
   // SyncShare (e.g., HasMoreToSync returned true).
@@ -165,6 +177,9 @@
   // Returns the set of enabled groups that have conflicts.
   std::set<ModelSafeGroup> GetEnabledGroupsWithConflicts() const;
 
+  // Mark the session has having finished all the sync steps it needed.
+  void SetFinished();
+
  private:
   // Extend the encapsulation boundary to utilities for internal member
   // assignments. This way, the scope of these actions is explicit, they can't
@@ -202,6 +217,10 @@
   // |routing_info_|.
   std::set<ModelSafeGroup> enabled_groups_;
 
+  // Whether this session has reached its last step or not. Gets reset on each
+  // new cycle (via PrepareForAnotherSyncCycle).
+  bool finished_;
+
   DISALLOW_COPY_AND_ASSIGN(SyncSession);
 };