[Sync] Remove ModelChangingSyncerCommand::HasCustomGroups()

chrome/browser/sync/engine/model_changing_syncer_command.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.
 
 #ifndef CHROME_BROWSER_SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_
 #define CHROME_BROWSER_SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_
 #pragma once
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/sync/engine/model_safe_worker.h"
@@ skipping 30 matching lines @@
     ModelChangingExecuteImpl(work_session_);
     return UnrecoverableErrorInfo();
   }
 
   std::set<ModelSafeGroup> GetGroupsToChangeForTest(
       const sessions::SyncSession& session) const {
     return GetGroupsToChange(session);
   }
 
  protected:
-  // Hack to track down which subclass triggers the perf regression.
-  // (See comments in http://codereview.chromium.org/8637006/ for
-  // details.)  If this returns false (the default),
-  // GetGroupsToChange() is not used and session.GetEnabledGroups()
-  // is used instead.
-  //
-  // TODO(akalin): Remove this when we track down the perf regression.
-  virtual bool HasCustomGroupsToChange() const = 0;
-
   // This should return the set of groups in |session| that need to be
   // changed.  The returned set should be a subset of
   // session.GetEnabledGroups().  Subclasses can guarantee this either
   // by calling one of the session.GetEnabledGroups*() functions and
   // filtering that, or using GetGroupForModelType() (which handles
   // top-level/unspecified nodes) to project from model types to
   // groups.
   virtual std::set<ModelSafeGroup> GetGroupsToChange(
       const sessions::SyncSession& session) const = 0;
 
@@ skipping 17 matching lines @@
   // Implementations will implement ModelChangingExecuteImpl and not
   // worry about storing the session or setting it. They are given work_session.
   sessions::SyncSession* work_session_;
 
   DISALLOW_COPY_AND_ASSIGN(ModelChangingSyncerCommand);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_ENGINE_MODEL_CHANGING_SYNCER_COMMAND_H_