sync: centralize sync startup decisions in TryStart.

chrome/browser/sync/profile_sync_service.h

 // Copyright (c) 2012 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_PROFILE_SYNC_SERVICE_H_
 #define CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_
 
 #include <list>
 #include <string>
 
@@ skipping 572 matching lines @@
       const std::string& payload);
 
  protected:
   // Used by test classes that derive from ProfileSyncService.
   virtual browser_sync::SyncBackendHost* GetBackendForTest();
 
   // Helper to install and configure a data type manager.
   void ConfigureDataTypeManager();
 
   // Starts up the backend sync components.
-  void StartUp();
+  virtual void StartUp();
   // Shuts down the backend sync components.
   // |sync_disabled| indicates if syncing is being disabled or not.
   void ShutdownImpl(bool sync_disabled);
 
   // Return SyncCredentials from the TokenService.
   syncer::SyncCredentials GetCredentials();
 
   // Test need to override this to create backends that allow setting up
   // initial conditions, such as populating sync nodes.
   //
@@ skipping 274 matching lines @@
   syncer::WeakHandle<syncer::DataTypeDebugInfoListener> debug_info_listener_;
 
   DISALLOW_COPY_AND_ASSIGN(ProfileSyncService);
 };
 
 bool ShouldShowActionOnUI(
     const syncer::SyncProtocolError& error);
 
 
 #endif  // CHROME_BROWSER_SYNC_PROFILE_SYNC_SERVICE_H_