Cache Backend Proxy to intercept all cache events from the IO thread.

net/disk_cache/disk_cache_test_base.cc

Index: net/disk_cache/disk_cache_test_base.cc
diff --git a/net/disk_cache/disk_cache_test_base.cc b/net/disk_cache/disk_cache_test_base.cc
index df913fbf5484031bbf9563545cc1d2177cf9c3ef..2706c351a39760515c329ddebe8726a17a7cf923 100644
--- a/net/disk_cache/disk_cache_test_base.cc
+++ b/net/disk_cache/disk_cache_test_base.cc
@@ -74,7 +74,8 @@ void DiskCacheTestWithCache::InitCache() {
     InitDiskCache();
 
   ASSERT_TRUE(NULL != cache_);
-  if (first_cleanup_)
+  // TODO(pasko): enable Entry Count for the Simple Cache.
+  if (first_cleanup_ && !simple_cache_mode_)
     ASSERT_EQ(0, cache_->GetEntryCount());
 }