Make time_to_first_suspension's default 1800sec

chrome/browser/memory/tab_manager_unittest.cc

Index: chrome/browser/memory/tab_manager_unittest.cc
diff --git a/chrome/browser/memory/tab_manager_unittest.cc b/chrome/browser/memory/tab_manager_unittest.cc
index 59b93b6cec30027077c4c3b79573c61c3c5583ad..91293fa87d02f198845287cf35833dd74f94f5f6 100644
--- a/chrome/browser/memory/tab_manager_unittest.cc
+++ b/chrome/browser/memory/tab_manager_unittest.cc
@@ -681,7 +681,9 @@ TEST_F(TabManagerTest, NextPurgeAndSuspendState) {
   WebContents* test_contents = CreateWebContents();
   tabstrip.AppendWebContents(test_contents, false);
 
-  base::TimeDelta threshold = base::TimeDelta::FromSeconds(180);
+  // Use default time-to-first-suspension seconds defined in TabManager.
+  base::TimeDelta threshold = base::TimeDelta::FromSeconds(
+      TabManager::kDefaultTimeToFirstPurgeInSeconds);
   base::SimpleTestTickClock test_clock;
 
   tab_manager.GetWebContentsData(test_contents)
@@ -689,11 +691,13 @@ TEST_F(TabManagerTest, NextPurgeAndSuspendState) {
   tab_manager.GetWebContentsData(test_contents)
       ->SetLastPurgeAndSuspendModifiedTimeForTesting(test_clock.NowTicks());
 
-  test_clock.Advance(base::TimeDelta::FromSeconds(180));
+  // Wait 30 minutes. Should be still RUNNING.

[Wez, 2017/02/22 01:25:10]

nit: Comment style is to prefer complete sentences, e.g. "Wait 30 minutes and
verify that the tab is still RUNNING." and then "Wait another second and verify
that it is now SUSPENDED."

[tasak, 2017/02/22 04:18:46]

Done.

+  test_clock.Advance(base::TimeDelta::FromMinutes(30));
   EXPECT_EQ(TabManager::RUNNING,
             tab_manager.GetNextPurgeAndSuspendState(
                 test_contents, test_clock.NowTicks(), threshold));
 
+  // > 30 minutes. Should be still SUSPENDED.

[Wez, 2017/02/22 01:25:10]

Do you mean "Should _now_ be SUSPENDED."?

[tasak, 2017/02/22 04:18:46]

Yes, thanks.
Done.

   test_clock.Advance(base::TimeDelta::FromSeconds(1));
   EXPECT_EQ(TabManager::SUSPENDED,
             tab_manager.GetNextPurgeAndSuspendState(