Let prefetched resources skip cache revalidation once for a short duration.

net/http/http_transaction_test_util.h

Index: net/http/http_transaction_test_util.h
diff --git a/net/http/http_transaction_test_util.h b/net/http/http_transaction_test_util.h
index e6e831257e878a8b6d87083229ebab535db5ef7d..cd4a49fc342ee2e3839a4dbc3b68c483fe255747 100644
--- a/net/http/http_transaction_test_util.h
+++ b/net/http/http_transaction_test_util.h
@@ -291,11 +291,26 @@ class MockNetworkLayer : public net::HttpTransactionFactory,
   net::HttpCache* GetCache() override;
   net::HttpNetworkSession* GetSession() override;
 
+  // The caller must guarantee that |clock| will outlive this object.
+  void set_clock(base::Clock* clock) {
+    DCHECK(!clock_);

[rvargas (doing something else), 2015/01/09 02:25:34]

Logging doesn't qualify anymore as trivial accessor. (and it's a good practice
to avoid logging from header files)

[jkarlin, 2015/01/09 14:03:51]

Done.

+    clock_ = clock;
+  }
+  base::Clock* clock() const { return clock_; }
+
+  // The current time (will use clock_ if it is non NULL).
+  base::Time Now();
+
  private:
   int transaction_count_;
   bool done_reading_called_;
   bool stop_caching_called_;
   net::RequestPriority last_create_transaction_priority_;
+
+  // By default clock_ is NULL but it can be set to a custom clock by test
+  // frameworks using set_clock.
+  base::Clock* clock_;
+
   base::WeakPtr<MockNetworkTransaction> last_transaction_;
 };