[Quota] Move quota related callbacks to separate file

webkit/quota/usage_tracker.h

 // 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.
 
 #ifndef WEBKIT_QUOTA_USAGE_TRACKER_H_
 #define WEBKIT_QUOTA_USAGE_TRACKER_H_
 
 #include <list>
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "googleurl/src/gurl.h"
+#include "webkit/quota/quota_callbacks.h"
 #include "webkit/quota/quota_client.h"
 #include "webkit/quota/quota_task.h"
 #include "webkit/quota/quota_types.h"
 #include "webkit/quota/special_storage_policy.h"
 
 namespace quota {
 
 class ClientUsageTracker;
 
 // A helper class that gathers and tracks the amount of data stored in
@@ skipping 148 matching lines @@
   HostUsageAccumulatorMap host_usage_accumulators_;
 
   scoped_refptr<SpecialStoragePolicy> special_storage_policy_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientUsageTracker);
 };
 
 }  // namespace quota
 
 #endif  // WEBKIT_QUOTA_USAGE_TRACKER_H_