Make time_to_first_suspension's default 1800sec

chrome/browser/memory/tab_manager.h

Index: chrome/browser/memory/tab_manager.h
diff --git a/chrome/browser/memory/tab_manager.h b/chrome/browser/memory/tab_manager.h
index 0e2d48a8b0bd40bec5a18596dd952e9e51bb1bbe..37933e54b104d050b4dddef70a3242f0f9c9174f 100644
--- a/chrome/browser/memory/tab_manager.h
+++ b/chrome/browser/memory/tab_manager.h
@@ -178,6 +178,12 @@ class TabManager : public TabStripModelObserver {
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, TabManagerBasics);
   FRIEND_TEST_ALL_PREFIXES(TabManagerWebContentsDataTest, PurgeAndSuspendState);
 
+  // The time of the first purging after a renderer is backgrounded.
+  // There is no strong reason why its default value is 30 minutes.

[Wez, 2017/02/17 19:03:14]

nit: No need to say "no strong reason"; sufficient to say "this initial value
was chosen to <reason>", for example.

[tasak, 2017/02/20 07:07:15]

Done.

+  // At least, the value should not be small, because quickly purging memory
+  // makes it slower to switch tabs.
+  static const int kDefaultTimeToFirstSuspensionSeconds = 1800;

[Wez, 2017/02/17 19:03:14]

Note that you'll also need to fix this in the Finch configuration.

[Wez, 2017/02/17 19:03:14]

nit: I'd suggest using "Suspend" rather than "Suspension" here, so that it's
easy for someone doing a dumb search through the code for "Suspend" to find the
constant.  However, I'd also recommend naming it according to what it actually
does, so kDefaultTimeToFirstPurgeInSeconds, for example.

[tasak, 2017/02/20 07:07:15]

Done.

[tasak, 2017/02/20 07:07:15]

Acknowledged.

+
   // This is needed so WebContentsData can call OnDiscardedStateChange, and
   // can use PurgeAndSuspendState.
   friend class WebContentsData;