Add a size estimation mechanism to StoragePartitionHttpCacheDataRemover.

net/disk_cache/simple/simple_backend_impl.cc

Index: net/disk_cache/simple/simple_backend_impl.cc
diff --git a/net/disk_cache/simple/simple_backend_impl.cc b/net/disk_cache/simple/simple_backend_impl.cc
index 5d1730f883f2cf5db12c8dd77ab8ab5352f17934..d3db3865349897d962818043675bb2eaaaba205c 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -470,6 +470,14 @@ int SimpleBackendImpl::DoomEntriesSince(
   return DoomEntriesBetween(initial_time, Time(), callback);
 }
 
+int SimpleBackendImpl::CalculateSizeOfEntriesBetween(
+    base::Time initial_time,
+    base::Time end_time,
+    const CompletionCallback& callback) {
+  // TODO(msramek): Implement.

[pasko, 2015/09/04 14:11:50]

for implementation I would suggest to wait for index to get ready:
index_->ExecuteWhenReady() then just go through all 
entries_set_ and ask for GetEntrySize() there.

[msramek, 2015/09/04 16:56:47]

Acknowledged. But if you don't mind, I'll do that in a followup CL. I'll make
sure to include you as a reviewer.

(I want to do each backend separately, but I had to put the infrastructure in
place first)

[pasko, 2015/09/08 13:13:49]

sure, sorry for the confusion, I only wrote it to help with future CL(s)

+  return net::ERR_NOT_IMPLEMENTED;
+}
+
 class SimpleBackendImpl::SimpleIterator final : public Iterator {
  public:
   explicit SimpleIterator(base::WeakPtr<SimpleBackendImpl> backend)