Remove dead code

chrome/browser/history/history_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.
 
 // The history system runs on a background thread so that potentially slow
 // database operations don't delay the browser. This backend processing is
 // represented by HistoryBackend. The HistoryService's job is to dispatch to
 // that thread.
 //
 // Main thread                       History thread
@@ skipping 273 matching lines @@
   // Delete the thread, which joins with the background thread. We defensively
   // NULL the pointer before deleting it in case somebody tries to use it
   // during shutdown, but this shouldn't happen.
   base::Thread* thread = thread_;
   thread_ = NULL;
   delete thread;
 }
 
 void HistoryService::ClearCachedDataForContextID(
     history::ContextID context_id) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::ClearCachedDataForContextID, context_id);
 }
 
 history::URLDatabase* HistoryService::InMemoryDatabase() {
   DCHECK(thread_checker_.CalledOnValidThread());
   return in_memory_backend_ ? in_memory_backend_->db() : NULL;
 }
 
@@ skipping 31 matching lines @@
 }
 
 void HistoryService::Shutdown() {
   DCHECK(thread_checker_.CalledOnValidThread());
   Cleanup();
 }
 
 void HistoryService::SetKeywordSearchTermsForURL(const GURL& url,
                                                  KeywordID keyword_id,
                                                  const base::string16& term) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_UI,
                     &HistoryBackend::SetKeywordSearchTermsForURL,
                     url, keyword_id, term);
 }
 
 void HistoryService::DeleteAllSearchTermsForKeyword(KeywordID keyword_id) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (in_memory_backend_)
     in_memory_backend_->DeleteAllSearchTermsForKeyword(keyword_id);
 
   ScheduleAndForget(PRIORITY_UI,
                     &HistoryBackend::DeleteAllSearchTermsForKeyword,
                     keyword_id);
 }
 
 void HistoryService::DeleteKeywordSearchTermForURL(const GURL& url) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_UI, &HistoryBackend::DeleteKeywordSearchTermForURL,
                     url);
 }
 
 void HistoryService::DeleteMatchingURLsForKeyword(KeywordID keyword_id,
                                                   const base::string16& term) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_UI, &HistoryBackend::DeleteMatchingURLsForKeyword,
                     keyword_id, term);
 }
 
 void HistoryService::URLsNoLongerBookmarked(const std::set<GURL>& urls) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::URLsNoLongerBookmarked,
                     urls);
 }
 
 void HistoryService::ScheduleDBTask(scoped_refptr<history::HistoryDBTask> task,
                                     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   base::CancelableTaskTracker::IsCanceledCallback is_canceled;
   tracker->NewTrackedTaskId(&is_canceled);
   // Use base::ThreadTaskRunnerHandler::Get() to get a message loop proxy to
   // the current message loop so that we can forward the call to the method
   // HistoryDBTask::DoneRunOnMainThread in the correct thread.
   thread_->message_loop_proxy()->PostTask(
       FROM_HERE,
       base::Bind(&HistoryBackend::ProcessDBTask,
                  history_backend_.get(),
                  task,
                  base::ThreadTaskRunnerHandle::Get(),
                  is_canceled));
 }
 
 void HistoryService::FlushForTest(const base::Closure& flushed) {
   thread_->message_loop_proxy()->PostTaskAndReply(
       FROM_HERE, base::Bind(&base::DoNothing), flushed);
 }
 
 void HistoryService::SetOnBackendDestroyTask(const base::Closure& task) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::SetOnBackendDestroyTask,
                     base::MessageLoop::current(), task);
 }
 
 void HistoryService::AddPage(const GURL& url,
                              Time time,
                              history::ContextID context_id,
                              int32 page_id,
                              const GURL& referrer,
@@ skipping 13 matching lines @@
                              history::VisitSource visit_source) {
   DCHECK(thread_checker_.CalledOnValidThread());
   AddPage(
       history::HistoryAddPageArgs(url, time, NULL, 0, GURL(),
                                   history::RedirectList(),
                                   content::PAGE_TRANSITION_LINK,
                                   visit_source, false));
 }
 
 void HistoryService::AddPage(const history::HistoryAddPageArgs& add_page_args) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(thread_) << "History service being called after cleanup";
 
   // Filter out unwanted URLs. We don't add auto-subframe URLs. They are a
   // large part of history (think iframes for ads) and we never display them in
   // history UI. We will still add manual subframes, which are ones the user
   // has clicked on to get.
   if (!CanAddURL(add_page_args.url))
     return;
 
   // Add link & all redirects to visited link list.
   if (visitedlink_master_) {
     visitedlink_master_->AddURL(add_page_args.url);
 
     if (!add_page_args.redirects.empty()) {
       // We should not be asked to add a page in the middle of a redirect chain.
       DCHECK_EQ(add_page_args.url,
                 add_page_args.redirects[add_page_args.redirects.size() - 1]);
 
       // We need the !redirects.empty() condition above since size_t is unsigned
       // and will wrap around when we subtract one from a 0 size.
       for (size_t i = 0; i < add_page_args.redirects.size() - 1; i++)
         visitedlink_master_->AddURL(add_page_args.redirects[i]);
     }
   }
 
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::AddPage, add_page_args);
 }
 
 void HistoryService::AddPageNoVisitForBookmark(const GURL& url,
                                                const base::string16& title) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!CanAddURL(url))
     return;
 
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::AddPageNoVisitForBookmark, url, title);
 }
 
 void HistoryService::SetPageTitle(const GURL& url,
                                   const base::string16& title) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::SetPageTitle, url, title);
 }
 
 void HistoryService::UpdateWithPageEndTime(history::ContextID context_id,
                                            int32 page_id,
                                            const GURL& url,
                                            Time end_ts) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::UpdateWithPageEndTime,
                     context_id, page_id, url, end_ts);
 }
 
 void HistoryService::AddPageWithDetails(const GURL& url,
                                         const base::string16& title,
                                         int visit_count,
                                         int typed_count,
                                         Time last_visit,
                                         bool hidden,
                                         history::VisitSource visit_source) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   // Filter out unwanted URLs.
   if (!CanAddURL(url))
     return;
 
   // Add to the visited links system.
   if (visitedlink_master_)
     visitedlink_master_->AddURL(url);
 
   history::URLRow row(url);
   row.set_title(title);
   row.set_visit_count(visit_count);
   row.set_typed_count(typed_count);
   row.set_last_visit(last_visit);
   row.set_hidden(hidden);
 
   history::URLRows rows;
   rows.push_back(row);
 
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::AddPagesWithDetails, rows, visit_source);
 }
 
 void HistoryService::AddPagesWithDetails(const history::URLRows& info,
                                          history::VisitSource visit_source) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   // Add to the visited links system.
   if (visitedlink_master_) {
     std::vector<GURL> urls;
     urls.reserve(info.size());
     for (history::URLRows::const_iterator i = info.begin(); i != info.end();
          ++i)
       urls.push_back(i->url());
 
     visitedlink_master_->AddURLs(urls);
   }
 
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::AddPagesWithDetails, info, visit_source);
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::GetFavicons(
     const std::vector<GURL>& icon_urls,
     int icon_types,
     const std::vector<int>& desired_sizes,
     const favicon_base::FaviconResultsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-
   std::vector<favicon_base::FaviconRawBitmapResult>* results =
       new std::vector<favicon_base::FaviconRawBitmapResult>();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::GetFavicons,
                  history_backend_.get(),
                  icon_urls,
                  icon_types,
                  desired_sizes,
                  results),
       base::Bind(&RunWithFaviconResults, callback, base::Owned(results)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::GetFaviconsForURL(
     const GURL& page_url,
     int icon_types,
     const std::vector<int>& desired_sizes,
     const favicon_base::FaviconResultsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-
   std::vector<favicon_base::FaviconRawBitmapResult>* results =
       new std::vector<favicon_base::FaviconRawBitmapResult>();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::GetFaviconsForURL,
                  history_backend_.get(),
                  page_url,
                  icon_types,
                  desired_sizes,
                  results),
       base::Bind(&RunWithFaviconResults, callback, base::Owned(results)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::GetLargestFaviconForURL(
     const GURL& page_url,
     const std::vector<int>& icon_types,
     int minimum_size_in_pixels,
     const favicon_base::FaviconRawBitmapCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-
   favicon_base::FaviconRawBitmapResult* result =
       new favicon_base::FaviconRawBitmapResult();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::GetLargestFaviconForURL,
                  history_backend_.get(),
                  page_url,
                  icon_types,
                  minimum_size_in_pixels,
                  result),
       base::Bind(&RunWithFaviconResult, callback, base::Owned(result)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::GetFaviconForID(
     favicon_base::FaviconID favicon_id,
     int desired_size,
     const favicon_base::FaviconResultsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-
   std::vector<favicon_base::FaviconRawBitmapResult>* results =
       new std::vector<favicon_base::FaviconRawBitmapResult>();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::GetFaviconForID,
                  history_backend_.get(),
                  favicon_id,
                  desired_size,
                  results),
       base::Bind(&RunWithFaviconResults, callback, base::Owned(results)));
 }
 
 base::CancelableTaskTracker::TaskId
 HistoryService::UpdateFaviconMappingsAndFetch(
     const GURL& page_url,
     const std::vector<GURL>& icon_urls,
     int icon_types,
     const std::vector<int>& desired_sizes,
     const favicon_base::FaviconResultsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-
   std::vector<favicon_base::FaviconRawBitmapResult>* results =
       new std::vector<favicon_base::FaviconRawBitmapResult>();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::UpdateFaviconMappingsAndFetch,
                  history_backend_.get(),
                  page_url,
                  icon_urls,
                  icon_types,
                  desired_sizes,
                  results),
       base::Bind(&RunWithFaviconResults, callback, base::Owned(results)));
 }
 
 void HistoryService::MergeFavicon(
     const GURL& page_url,
     const GURL& icon_url,
     favicon_base::IconType icon_type,
     scoped_refptr<base::RefCountedMemory> bitmap_data,
     const gfx::Size& pixel_size) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!CanAddURL(page_url))
     return;
 
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::MergeFavicon, page_url,
                     icon_url, icon_type, bitmap_data, pixel_size);
 }
 
 void HistoryService::SetFavicons(
     const GURL& page_url,
     favicon_base::IconType icon_type,
     const std::vector<favicon_base::FaviconRawBitmapData>&
         favicon_bitmap_data) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!CanAddURL(page_url))
     return;
 
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::SetFavicons, page_url,
       icon_type, favicon_bitmap_data);
 }
 
 void HistoryService::SetFaviconsOutOfDateForPage(const GURL& page_url) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::SetFaviconsOutOfDateForPage, page_url);
 }
 
 void HistoryService::CloneFavicons(const GURL& old_page_url,
                                    const GURL& new_page_url) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::CloneFavicons,
                     old_page_url, new_page_url);
 }
 
 void HistoryService::SetImportedFavicons(
     const std::vector<ImportedFaviconUsage>& favicon_usage) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::SetImportedFavicons, favicon_usage);
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryURL(
     const GURL& url,
     bool want_visits,
     const QueryURLCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::QueryURLResult* query_url_result = new history::QueryURLResult();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryURL,
                  history_backend_.get(),
                  url,
                  want_visits,
                  base::Unretained(query_url_result)),
@@ skipping 42 matching lines @@
   // Bind's arguments.
   thread_->message_loop_proxy()->PostTaskAndReply(
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryDownloads, history_backend_.get(), rows),
       base::Bind(callback, base::Passed(&scoped_rows)));
 }
 
 // Handle updates for a particular download. This is a 'fire and forget'
 // operation, so we don't need to be called back.
 void HistoryService::UpdateDownload(const history::DownloadRow& data) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::UpdateDownload, data);
 }
 
 void HistoryService::RemoveDownloads(const std::set<uint32>& ids) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::RemoveDownloads, ids);
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryHistory(
     const base::string16& text_query,
     const history::QueryOptions& options,
     const QueryHistoryCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::QueryResults* query_results = new history::QueryResults();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryHistory,
                  history_backend_.get(),
                  text_query,
                  options,
                  base::Unretained(query_results)),
       base::Bind(callback, base::Owned(query_results)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryRedirectsFrom(
     const GURL& from_url,
     const QueryRedirectsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::RedirectList* result = new history::RedirectList();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryRedirectsFrom,
                  history_backend_.get(),
                  from_url,
                  base::Unretained(result)),
       base::Bind(callback, base::Owned(result)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryRedirectsTo(
     const GURL& to_url,
     const QueryRedirectsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::RedirectList* result = new history::RedirectList();
   return tracker->PostTaskAndReply(thread_->message_loop_proxy().get(),
                                    FROM_HERE,
                                    base::Bind(&HistoryBackend::QueryRedirectsTo,
                                               history_backend_.get(),
                                               to_url,
                                               base::Unretained(result)),
                                    base::Bind(callback, base::Owned(result)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::GetVisibleVisitCountToHost(
     const GURL& url,
     const GetVisibleVisitCountToHostCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::VisibleVisitCountToHostResult* result =
       new history::VisibleVisitCountToHostResult();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::GetVisibleVisitCountToHost,
                  history_backend_.get(),
                  url,
                  base::Unretained(result)),
       base::Bind(&RunWithVisibleVisitCountToHostResult,
                  callback,
                  base::Owned(result)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryMostVisitedURLs(
     int result_count,
     int days_back,
     const QueryMostVisitedURLsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::MostVisitedURLList* result = new history::MostVisitedURLList();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryMostVisitedURLs,
                  history_backend_.get(),
                  result_count,
                  days_back,
                  base::Unretained(result)),
       base::Bind(callback, base::Owned(result)));
 }
 
 base::CancelableTaskTracker::TaskId HistoryService::QueryFilteredURLs(
     int result_count,
     const history::VisitFilter& filter,
     bool extended_info,
     const QueryFilteredURLsCallback& callback,
     base::CancelableTaskTracker* tracker) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   history::FilteredURLList* result = new history::FilteredURLList();
   return tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::QueryFilteredURLs,
                  history_backend_.get(),
                  result_count,
                  filter,
                  extended_info,
@@ skipping 32 matching lines @@
       break;
     }
 
     default:
       NOTREACHED();
   }
 }
 
 void HistoryService::RebuildTable(
     const scoped_refptr<URLEnumerator>& enumerator) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::IterateURLs, enumerator);
 }
 
 bool HistoryService::Init(const base::FilePath& history_dir, bool no_db) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   base::Thread::Options options;
   options.timer_slack = base::TIMER_SLACK_MAXIMUM;
   if (!thread_->StartWithOptions(options)) {
     Cleanup();
     return false;
   }
 
   history_dir_ = history_dir;
   no_db_ = no_db;
@@ skipping 128 matching lines @@
   in_memory_backend_->AttachToHistoryService(profile_);
 }
 
 void HistoryService::NotifyProfileError(sql::InitStatus init_status) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (history_client_)
     history_client_->NotifyProfileError(init_status);
 }
 
 void HistoryService::DeleteURL(const GURL& url) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   // We will update the visited links when we observe the delete notifications.
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::DeleteURL, url);
 }
 
 void HistoryService::DeleteURLsForTest(const std::vector<GURL>& urls) {
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
   // We will update the visited links when we observe the delete
   // notifications.
   ScheduleAndForget(PRIORITY_NORMAL, &HistoryBackend::DeleteURLs, urls);
 }
 
 void HistoryService::ExpireHistoryBetween(
     const std::set<GURL>& restrict_urls,
     Time begin_time,
     Time end_time,
     const base::Closure& callback,
     base::CancelableTaskTracker* tracker) {
-  DCHECK(thread_);
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(history_backend_.get());
   tracker->PostTaskAndReply(thread_->message_loop_proxy().get(),
                             FROM_HERE,
                             base::Bind(&HistoryBackend::ExpireHistoryBetween,
                                        history_backend_,
                                        restrict_urls,
                                        begin_time,
                                        end_time),
                             callback);
 }
 
 void HistoryService::ExpireHistory(
     const std::vector<history::ExpireHistoryArgs>& expire_list,
     const base::Closure& callback,
     base::CancelableTaskTracker* tracker) {
-  DCHECK(thread_);
+  DCHECK(thread_) << "History service being called after cleanup";
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(history_backend_.get());
   tracker->PostTaskAndReply(
       thread_->message_loop_proxy().get(),
       FROM_HERE,
       base::Bind(&HistoryBackend::ExpireHistory, history_backend_, expire_list),
       callback);
 }
 
 void HistoryService::ExpireLocalAndRemoteHistoryBetween(
     const std::set<GURL>& restrict_urls,
     Time begin_time,
@@ skipping 75 matching lines @@
   DCHECK(thread_checker_.CalledOnValidThread());
   visit_database_observers_.RemoveObserver(observer);
 }
 
 void HistoryService::NotifyVisitDBObserversOnAddVisit(
     const history::BriefVisitInfo& info) {
   DCHECK(thread_checker_.CalledOnValidThread());
   FOR_EACH_OBSERVER(history::VisitDatabaseObserver, visit_database_observers_,
                     OnAddVisit(info));
 }