[WIP] histroy: Adjust cache size OnMemoryStateChange()

components/history/core/browser/history_backend.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 "components/history/core/browser/history_backend.h"
 
 #include <algorithm>
 #include <functional>
 #include <list>
 #include <map>
@@ skipping 903 matching lines @@
   NotifyURLsModified(changed_urls);
   ScheduleCommit();
 }
 
 bool HistoryBackend::IsExpiredVisitTime(const base::Time& time) {
   return time < expirer_.GetCurrentExpirationTime();
 }
 
 void HistoryBackend::OnMemoryStateChange(
     memory_coordinator::MemoryState state) {
-  bool trim_aggressively = state == memory_coordinator::MemoryState::SUSPENDED;
-  TrimMemory(trim_aggressively);
+  db_->AdjustCacheMemory(state);
+  // TODO(bashi): Adjust cache memory of |thumbnail_db_| as well.
 }
 
 void HistoryBackend::SetPageTitle(const GURL& url,
                                   const base::string16& title) {
   if (!db_)
     return;
 
   // Search for recent redirects which should get the same title. We make a
   // dummy list containing the exact URL visited if there are no redirects so
   // the processing below can be the same.
@@ skipping 1721 matching lines @@
   // transaction is currently open.
   db_->CommitTransaction();
   db_->Vacuum();
   db_->BeginTransaction();
   db_->GetStartDate(&first_recorded_time_);
 
   return true;
 }
 
 }  // namespace history