Make TokenService drop its ref to WebDataService in Shutdown() rather than dtor.

chrome/browser/signin/token_service.cc

 // 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.
 
 #include "chrome/browser/signin/token_service.h"
 
 #include "base/basictypes.h"
 #include "base/command_line.h"
 #include "base/prefs/pref_service.h"
 #include "base/string_util.h"
@@ skipping 41 matching lines @@
       token_loading_query_(0),
       tokens_loaded_(false) {
   // Allow constructor to be called outside the UI thread, so it can be mocked
   // out for unit tests.
 
   COMPILE_ASSERT(arraysize(kServices) == arraysize(fetchers_),
                  kServices_and_fetchers_dont_have_same_size);
 }
 
 TokenService::~TokenService() {
+}
+
+void TokenService::Shutdown() {
   if (!source_.empty()) {
     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     ResetCredentialsInMemory();
   }
+  web_data_service_ = NULL;
 }
 
 void TokenService::Initialize(const char* const source,
                               Profile* profile) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!source_.empty()) {
     // Already initialized.
     return;
   }
   DCHECK(!profile_);
@@ skipping 377 matching lines @@
 
 void TokenService::AddSigninDiagnosticsObserver(
     SigninDiagnosticsObserver* observer) {
   signin_diagnostics_observers_.AddObserver(observer);
 }
 
 void TokenService::RemoveSigninDiagnosticsObserver(
     SigninDiagnosticsObserver* observer) {
   signin_diagnostics_observers_.RemoveObserver(observer);
 }