Remove routing_info and workers from SyncSession

For all outward appearances, the SyncSession's workers and routing info
will always precisely mirror those found in the SyncSessionContext.  It
is equivalent, and much simpler, to grab the latest routing info from
the context wherever it's needed.

Any SyncSession that makes it to a sync cycle will either have been
initialized with the SyncSessionContext's routing info and workers, or
Coalesced (set union) and Rebased (set intersection) with the
SyncSessionContext's routing info and workers to the point where it's
effectively equivalent to copying the context's data.  Much of the logic
to implement this book-keeping has been simplified in this patch.

Configure mode is an important exception.  While configuring, we would
attempt to keep all currently enabled types enabled in the
SyncSessionContext, while passing a restricted amount of routing info
the the SyncSession.  It turns out that it's not necessary to allow the
SyncSessionContext and SyncSession routing info diverge in this case;
it's OK to set the context's routing info to the restricted routes.

In addition to trimming the session's routing info and workers list,
RebaseRoutingInfoWithLatest was also responsible for trimming the list
of notification hints to match the set of currently enabled types.  This
is redundant because the code in DownloadUpdatesCommand performs the
same filtering using the same routing info.  RebaseRoutingInfoWithLatest
had no remaining useful features, so it was removed entirely.

The Coalesce function still exists in a reduced form to handle merge
sources between sessions.  Its name and signature have been changed to
reflect its new responsibilities.

Without its own copy of the workers and routing info, the
SyncSessionContext can no longer easily calculate the set of enabled
groups.  Fortunately, that information is only accessed by a single test
case.  The relevant code was moved into this test case.

BUG=175024


Review URL: https://chromiumcodereview.appspot.com/12225091

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182756 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 35 deletions

diff --git a/sync/sessions/sync_session.h b/sync/sessions/sync_session.h
index 901e3b5..7271b5f 100644
--- a/sync/sessions/sync_session.h
+++ b/sync/sessions/sync_session.h
@@ -97,9 +97,7 @@ class SYNC_EXPORT_PRIVATE SyncSession {
 
   SyncSession(SyncSessionContext* context,
               Delegate* delegate,
-              const SyncSourceInfo& source,
-              const ModelSafeRoutingInfo& routing_info,
-              const std::vector<ModelSafeWorker*>& workers);
+              const SyncSourceInfo& source);
   ~SyncSession();
 
   // Builds a thread-safe and read-only copy of the current session state.
@@ -114,20 +112,9 @@ class SYNC_EXPORT_PRIVATE SyncSession {
   // See SERVER_RETURN_* in the SyncerError enum for values.
   bool DidReachServer() 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
-  // next SyncShare operation using |this|, rather than needed two separate
-  // 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
-  // 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);
+  // Overwrite the sync update source with the most recent and merge the
+  // type/state map.
+  void CoalesceSources(const SyncSourceInfo& source);
 
   // TODO(akalin): Split this into context() and mutable_context().
   SyncSessionContext* context() const { return context_; }
@@ -147,13 +134,8 @@ class SYNC_EXPORT_PRIVATE SyncSession {
     return &extensions_activity_;
   }
 
-  const std::vector<ModelSafeWorker*>& workers() const { return workers_; }
-  const ModelSafeRoutingInfo& routing_info() const { return routing_info_; }
   const SyncSourceInfo& source() const { return source_; }
 
-  // Returns the set of groups which have enabled types.
-  const std::set<ModelSafeGroup>& GetEnabledGroups() const;
-
  private:
   // Extend the encapsulation boundary to utilities for internal member
   // assignments. This way, the scope of these actions is explicit, they can't
@@ -182,19 +164,6 @@ class SYNC_EXPORT_PRIVATE SyncSession {
   // Our controller for various status and error counters.
   scoped_ptr<StatusController> status_controller_;
 
-  // The set of active ModelSafeWorkers for the duration of this session.
-  // This can change if this session is Coalesce()'d with another.
-  std::vector<ModelSafeWorker*> workers_;
-
-  // The routing info for the duration of this session, dictating which
-  // datatypes should be synced and which workers should be used when working
-  // on those datatypes.
-  ModelSafeRoutingInfo routing_info_;
-
-  // The set of groups with enabled types.  Computed from
-  // |routing_info_|.
-  std::set<ModelSafeGroup> enabled_groups_;
-
   DISALLOW_COPY_AND_ASSIGN(SyncSession);
 };