Make it clear what last_sync_timestamp actually tracks. Update

chrome/browser/sync/engine/syncapi.cc

 // Copyright (c) 2006-2009 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.
 
 #include "chrome/browser/sync/engine/syncapi.h"
 
 #include "build/build_config.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 1810 matching lines @@
           DCHECK(false) << "ScopedDirLookup creation failed; unable to hook "
                         << "up directory change event listener!";
           return;
         }
         dir_change_hookup_.reset(NewEventListenerHookup(
             lookup->changes_channel(), this,
             &SyncInternal::HandleChangeEvent));
 
         if (lookup->initial_sync_ended())
           MarkAndNotifyInitializationComplete();
-
-        // If we are transitioning from having bad to good credentials, that
-        // could mean that the syncer can now make forward progress.  Wake it.
-        syncer_thread_->NudgeSyncer(0, SyncerThread::kLocal);
       }
       return;
     // Authentication failures translate to GoogleServiceAuthError events.
     case AuthWatcherEvent::GAIA_AUTH_FAILED:     // Invalid GAIA credentials.
       if (event.auth_results->auth_error == browser_sync::CaptchaRequired) {
         auth_problem_ = AuthError::CAPTCHA_REQUIRED;
         std::string url_string("https://www.google.com/accounts/");
         url_string += event.auth_results->captcha_url;
         GURL captcha(url_string);
         observer_->OnAuthError(AuthError::FromCaptchaChallenge(
@@ skipping 89 matching lines @@
 BaseTransaction::~BaseTransaction() {
   delete lookup_;
 }
 
 UserShare* SyncManager::GetUserShare() const {
   DCHECK(data_->initialized()) << "GetUserShare requires initialization!";
   return data_->GetUserShare();
 }
 
 }  // namespace sync_api