[Sync] Made some sync session member functions const

chrome/browser/sync/sessions/sync_session.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // A class representing an attempt to synchronize the local syncable data
 // store with a sync server. A SyncSession instance is passed as a stateful
 // bundle to and from various SyncerCommands with the goal of converging the
 // client view of data with that of the server. The commands twiddle with
 // session status in response to events and hiccups along the way, set and
 // query session progress with regards to conflict resolution and applying
@@ skipping 107 matching lines @@
   // 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(SyncSession* session);
 
   // Should be called any time |this| is being re-used in a new call to
   // SyncShare (e.g., HasMoreToSync returned true).
   void ResetTransientState();
 
+  // TODO(akalin): Split this into context() and mutable_context().
   SyncSessionContext* context() const { return context_; }
   Delegate* delegate() const { return delegate_; }
   syncable::WriteTransaction* write_transaction() { return write_transaction_; }
-  StatusController* status_controller() { return status_controller_.get(); }
+  const StatusController& status_controller() const {
+    return *status_controller_.get();
+  }
+  StatusController* mutable_status_controller() {
+    return status_controller_.get();
+  }
 
   const ExtensionsActivityMonitor::Records& extensions_activity() const {
     return extensions_activity_;
   }
   ExtensionsActivityMonitor::Records* mutable_extensions_activity() {
     return &extensions_activity_;
   }
 
   // Volatile reader for the source member of the sync session object.  The
   // value is set to the SYNC_CYCLE_CONTINUATION value to signal that it has
@@ skipping 55 matching lines @@
 
  private:
   SyncSession* session_;
   DISALLOW_COPY_AND_ASSIGN(ScopedSetSessionWriteTransaction);
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSION_H_