Add a size estimation mechanism to StoragePartitionHttpCacheDataRemover.

net/disk_cache/disk_cache.h

 // 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.
 
 // Defines the public interface of the disk cache. For more details see
 // http://dev.chromium.org/developers/design-documents/network-stack/disk-cache
 
 #ifndef NET_DISK_CACHE_DISK_CACHE_H_
 #define NET_DISK_CACHE_DISK_CACHE_H_
 
@@ skipping 127 matching lines @@
                                  base::Time end_time,
                                  const CompletionCallback& callback) = 0;
 
   // Marks all entries accessed since |initial_time| for deletion. The return
   // value is a net error code. If this method returns ERR_IO_PENDING, the
   // |callback| will be invoked when the operation completes.
   // Entries with |initial_time| <= access time are deleted.
   virtual int DoomEntriesSince(base::Time initial_time,
                                const CompletionCallback& callback) = 0;
 
+  // Calculate the total size of the cache. The return value is the size in
+  // bytes or a net error code. If this method returns ERR_IO_PENDING,
+  // the |callback| will be invoked when the operation completes.
+  virtual int CalculateSizeOfAllEntries(
+      const CompletionCallback& callback) = 0;
+
   // Returns an iterator which will enumerate all entries of the cache in an
   // undefined order.
   virtual scoped_ptr<Iterator> CreateIterator() = 0;
 
   // Return a list of cache statistics.
   virtual void GetStats(base::StringPairs* stats) = 0;
 
   // Called whenever an external cache in the system reuses the resource
   // referred to by |key|.
   virtual void OnExternalCacheHit(const std::string& key) = 0;
@@ skipping 160 matching lines @@
     entry->Close();
   }
 };
 
 // Automatically closes an entry when it goes out of scope.
 typedef scoped_ptr<Entry, EntryDeleter> ScopedEntryPtr;
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_DISK_CACHE_H_