Revert of Remove reference counting from HttpNetworkSession.

net/http/mock_http_cache.cc

Index: net/http/mock_http_cache.cc
diff --git a/net/http/mock_http_cache.cc b/net/http/mock_http_cache.cc
index 10f4c09f286fe01eaf21eb9aec7d63652e9f8f6e..d939a3d8f9692f9f6c8eeddeda0e97dd1ccc38ca 100644
--- a/net/http/mock_http_cache.cc
+++ b/net/http/mock_http_cache.cc
@@ -519,10 +519,13 @@
 
 //-----------------------------------------------------------------------------
 
-MockHttpCache::MockHttpCache() : MockHttpCache(new MockBackendFactory()) {}
+MockHttpCache::MockHttpCache()
+    : http_cache_(new MockNetworkLayer(), NULL, new MockBackendFactory()) {
+}
 
 MockHttpCache::MockHttpCache(HttpCache::BackendFactory* disk_cache_factory)
-    : http_cache_(new MockNetworkLayer(), nullptr, disk_cache_factory, true) {}
+    : http_cache_(new MockNetworkLayer(), NULL, disk_cache_factory) {
+}
 
 disk_cache::Backend* MockHttpCache::backend() {
   TestCompletionCallback cb;