Add a size estimation mechanism to StoragePartitionHttpCacheDataRemover.

net/disk_cache/simple/simple_backend_impl.h

Index: net/disk_cache/simple/simple_backend_impl.h
diff --git a/net/disk_cache/simple/simple_backend_impl.h b/net/disk_cache/simple/simple_backend_impl.h
index 7993fdcd85343c02c3eea9baf2e63d50009744a6..95a3d4907670f5730541f9dc986b96324c84f0e1 100644
--- a/net/disk_cache/simple/simple_backend_impl.h
+++ b/net/disk_cache/simple/simple_backend_impl.h
@@ -105,6 +105,10 @@ class NET_EXPORT_PRIVATE SimpleBackendImpl : public Backend,
                          const CompletionCallback& callback) override;
   int DoomEntriesSince(base::Time initial_time,
                        const CompletionCallback& callback) override;
+  int CalculateSizeOfEntriesBetween(
+      base::Time initial_time,
+      base::Time end_time,
+      const CompletionCallback& callback) override;
   scoped_ptr<Iterator> CreateIterator() override;
   void GetStats(base::StringPairs* stats) override;
   void OnExternalCacheHit(const std::string& key) override;