Reverts a commit that caused ASAN failures, and 2 dependent commits.

chrome/browser/safe_browsing/malware_details_unittest.cc

Index: chrome/browser/safe_browsing/malware_details_unittest.cc
diff --git a/chrome/browser/safe_browsing/malware_details_unittest.cc b/chrome/browser/safe_browsing/malware_details_unittest.cc
index 52fa63370656416284ec8c6c1e68085a8aef3616..67fdb68c00dfd0bc97b71ba0273b15b944b474a7 100644
--- a/chrome/browser/safe_browsing/malware_details_unittest.cc
+++ b/chrome/browser/safe_browsing/malware_details_unittest.cc
@@ -106,11 +106,11 @@ void WriteToEntry(disk_cache::Backend* cache, const std::string key,
 }
 
 void FillCache(net::URLRequestContextGetter* context_getter) {
-  net::TestCompletionCallback cb;
+  TestOldCompletionCallback cb;
   disk_cache::Backend* cache;
   int rv =
       context_getter->GetURLRequestContext()->http_transaction_factory()->
-      GetCache()->GetBackend(&cache, cb.callback());
+      GetCache()->GetBackend(&cache, &cb);
   ASSERT_EQ(net::OK, cb.GetResult(rv));
 
   std::string empty;