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..f985e58ae89f292cf7c46a6adce8cc296c7d5f88 100644
--- a/net/disk_cache/simple/simple_backend_impl.cc
+++ b/net/disk_cache/simple/simple_backend_impl.cc
@@ -470,6 +470,12 @@ int SimpleBackendImpl::DoomEntriesSince(
   return DoomEntriesBetween(initial_time, Time(), callback);
 }
 
+int SimpleBackendImpl::CalculateSizeOfAllEntries(
+    const CompletionCallback& callback) {
+  // TODO(msramek): Implement.
+  return net::ERR_NOT_IMPLEMENTED;
+}
+
 class SimpleBackendImpl::SimpleIterator final : public Iterator {
  public:
   explicit SimpleIterator(base::WeakPtr<SimpleBackendImpl> backend)