Fixes possible deadlock between history and bookmarks. The deadlock

chrome/browser/profiles/profile_impl.cc

 // 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.
 
 #include "chrome/browser/profiles/profile_impl.h"
 
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/environment.h"
 #include "base/file_path.h"
@@ skipping 786 matching lines @@
     top_sites_->Shutdown();
 
   if (history_service_.get())
     history_service_->Cleanup();
 
   if (io_data_.HasMainRequestContext() &&
       default_request_context_ == GetRequestContext()) {
     default_request_context_ = NULL;
   }
 
+  if (bookmark_bar_model_.get()) {
+    // It's possible that bookmarks haven't loaded and history is waiting for
+    // bookmarks to complete loading. In such a situation history can't
+    // shutdown. To break the deadlock we tell BookmarkModel it's about to be
+    // deleted so that it can release the signal history is waiting on, allowing
+    // history to shutdown. In such a scenario history sees an incorrect view of
+    // bookmarks, but it's better than a deadlock.
+    bookmark_bar_model_->Cleanup();
+  }
   // HistoryService may call into the BookmarkModel, as such we need to
   // delete HistoryService before the BookmarkModel. The destructor for
   // HistoryService will join with HistoryService's backend thread so that
   // by the time the destructor has finished we're sure it will no longer call
   // into the BookmarkModel.
   history_service_ = NULL;
   bookmark_bar_model_.reset();
 
   // FaviconService depends on HistoryServce so make sure we delete
   // HistoryService first.
@@ skipping 991 matching lines @@
 
 chrome_browser_net::Predictor* ProfileImpl::GetNetworkPredictor() {
   return predictor_;
 }
 
 SpellCheckProfile* ProfileImpl::GetSpellCheckProfile() {
   if (!spellcheck_profile_.get())
     spellcheck_profile_.reset(new SpellCheckProfile());
   return spellcheck_profile_.get();
 }