Fix autoupdate_EndToEndTest on veyron_rialto

chrome/browser/chromeos/login/screens/network_screen_browsertest.cc

Index: chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
diff --git a/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc b/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
index 3337dee077b0bfb6d908f71d2c30787508113dc1..c30bd1bd07ae636b2ff4750825a9d8733dbf90ed 100644
--- a/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
+++ b/chrome/browser/chromeos/login/screens/network_screen_browsertest.cc
@@ -9,6 +9,7 @@
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/test/test_mock_time_task_runner.h"
 #include "chrome/browser/chromeos/login/enrollment/enrollment_screen.h"
 #include "chrome/browser/chromeos/login/helper.h"
 #include "chrome/browser/chromeos/login/screens/base_screen.h"
@@ -170,8 +171,16 @@ class HandsOffNetworkScreenTest : public NetworkScreenTest {
         ->GetShillManagerClient()
         ->GetTestInterface()
         ->SetupDefaultEnvironment();
+
+    // Set up mock TaskRunner.
+    base::TestMockTimeTaskRunner::ScopedContext scoped_context(

[xiyuan, 2017/04/18 22:45:26]

We need to make ScopedContext a member var of the test so that it will have the
same life time of the test. The original task runner is restored when
ScopedContext is destructed (i.e. go out of scope). That is probably why
FastFoward does not work.

+        task_runner_.get());
   }
 
+  // Replace main thread's task runner with a mock for duration of test.
+  scoped_refptr<base::TestMockTimeTaskRunner> task_runner_ =
+      new base::TestMockTimeTaskRunner();
+
  private:
   // Overridden from InProcessBrowserTest:
   void SetUpCommandLine(base::CommandLine* command_line) override {
@@ -259,6 +268,9 @@ IN_PROC_BROWSER_TEST_F(HandsOffNetworkScreenTest, ContinueClickedOnlyOnce) {
   // Stop waiting for net0.
   network_screen_->StopWaitingForConnection(base::ASCIIToUTF16("net0"));
 
+  // Fast forward time by 3 minutes.
+  task_runner_->FastForwardBy(base::TimeDelta::FromMinutes(3));
+
   // Check that OnContinueButtonPressed has been called exactly once.
   ASSERT_EQ(1, network_screen_->continue_attempts_);