[Sync] Add client-side plumbing for server control of sessions commit delay

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 52 matching lines @@
     virtual bool IsSyncingCurrentlySilenced() = 0;
 
     // The client has been instructed to change its short poll interval.
     virtual void OnReceivedShortPollIntervalUpdate(
         const base::TimeDelta& new_interval) = 0;
 
     // The client has been instructed to change its long poll interval.
     virtual void OnReceivedLongPollIntervalUpdate(
         const base::TimeDelta& new_interval) = 0;
 
+    // The client has been instructed to change its sessions commit
+    // delay.
+    virtual void OnReceivedSessionsCommitDelay(
+        const base::TimeDelta& new_delay) = 0;
+
     // The client needs to cease and desist syncing at once.  This occurs when
     // the Syncer detects that the backend store has fundamentally changed or
     // is a different instance altogether (e.g. swapping from a test instance
     // to production, or a global stop syncing operation has wiped the store).
     virtual void OnShouldStopSyncingPermanently() = 0;
 
    protected:
     virtual ~Delegate() {}
   };
 
@@ skipping 100 matching lines @@
 
  private:
   SyncSession* session_;
   DISALLOW_COPY_AND_ASSIGN(ScopedSetSessionWriteTransaction);
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSION_H_