Make it clear what last_sync_timestamp actually tracks. Update

chrome/browser/sync/sessions/session_state.h

 // Copyright (c) 2009 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.
 
 // The 'sessions' namespace comprises all the pieces of state that are
 // combined to form a SyncSession instance. In that way, it can be thought of
 // as an extension of the SyncSession type itself. Session scoping gives
 // context to things like "conflict progress", "update progress", etc, and the
 // separation this file provides allows clients to only include the parts they
 // need rather than the entire session stack.
@@ skipping 156 matching lines @@
   // Count the number of successful update applications that have happend this
   // cycle. Note that if an item is successfully applied twice, it will be
   // double counted here.
   int SuccessfullyAppliedUpdateCount() const;
 
   // Returns true if at least one update application failed due to a conflict
   // during this sync cycle.
   bool HasConflictingUpdates() const;
 
  private:
-  // Some container for updates that failed verification.
+  // Container for updates that passed verification.
   std::vector<VerifiedUpdate> verified_updates_;
 
   // Stores the result of the various ApplyUpdate attempts we've made.
   // May contain duplicate entries.
   std::vector<AppliedUpdate> applied_updates_;
 };
 
 struct SyncCycleControlParameters {
   SyncCycleControlParameters() : conflict_sets_built(false),
                                  conflicts_resolved(false),
-                                 items_committed(false),
-                                 got_new_timestamp(false) {}
+                                 items_committed(false) {}
   // Set to true by BuildAndProcessConflictSetsCommand if the RESOLVE_CONFLICTS
   // step is needed.
   bool conflict_sets_built;
 
   // Set to true by ResolveConflictsCommand if any forward progress was made.
   bool conflicts_resolved;
 
   // Set to true by PostCommitMessageCommand if any commits were successful.
   bool items_committed;
-
-  // The server sent us updates and a newer timestamp as part of the session.
-  bool got_new_timestamp;
 };
 
 // DirtyOnWrite wraps a value such that any write operation will update a
 // specified dirty bit, which can be used to determine if a notification should
 // be sent due to state change.
 template <typename T>
 class DirtyOnWrite {
  public:
   explicit DirtyOnWrite(bool* dirty) : dirty_(dirty) {}
   DirtyOnWrite(bool* dirty, const T& t) : t_(t), dirty_(dirty) {}
@@ skipping 50 matching lines @@
 struct PerModelTypeState {
   explicit PerModelTypeState(bool* dirty_flag)
       : current_sync_timestamp(dirty_flag, 0) {}
   DirtyOnWrite<int64> current_sync_timestamp;
 };
 
 }  // namespace sessions
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_SESSIONS_SESSION_STATE_H_