[Offline Pages] Add cached offline page utils and show usage in settings.

components/browsing_data/content/conditional_cache_counting_helper.h

 // Copyright 2016 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 COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_
 #define COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/disk_cache.h"
 
 namespace content {
 class StoragePartition;
 }
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace browsing_data {
 
 // Helper to count the size of the http cache data from a StoragePartition.
 class ConditionalCacheCountingHelper {
  public:
-  // Returns the number bytes in the selected range and if this value is an
-  // upper estimate.
-  typedef base::Callback<void(int64_t, bool)> CacheCountCallback;
+  // Returns if this value is an upper estimate and the number bytes in the
+  // selected range.
+  typedef base::Callback<void(bool, int64_t)> CacheCountCallback;
 
   static ConditionalCacheCountingHelper* CreateForRange(
       content::StoragePartition* storage_partition,
       base::Time begin_time,
       base::Time end_time);
 
   // Count the cache entries according to the specified time range. Destroys
   // this instance of ConditionalCacheCountingHelper when finished.
   // Must be called on the UI thread!
   //
@@ skipping 48 matching lines @@
   std::unique_ptr<disk_cache::Backend::Iterator> iterator_;
 
   base::WeakPtrFactory<ConditionalCacheCountingHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ConditionalCacheCountingHelper);
 };
 
 }  // namespace browsing_data
 
 #endif  // COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_