Make time_to_first_suspension's default 1800sec

chrome/browser/memory/tab_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/memory/tab_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 121 matching lines @@
     base::MemoryPressureListener::MemoryPressureLevel level) {
   content::MemoryPressureController::SendPressureNotification(
       render_process_host, level);
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // TabManager
 
+constexpr base::TimeDelta TabManager::kDefaultTimeToFirstPurge;
+
 TabManager::TabManager()
     : discard_count_(0),
       recent_tab_discard_(false),
       discard_once_(false),
 #if !defined(OS_CHROMEOS)
       minimum_protection_time_(base::TimeDelta::FromMinutes(10)),
 #endif
       browser_tab_strip_tracker_(this, nullptr, nullptr),
       test_tick_clock_(nullptr),
       under_memory_pressure_(false),
@@ skipping 67 matching lines @@
     if (level == base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL) {
       OnMemoryPressure(level);
     }
   }
 #endif
   // purge-and-suspend param is used for Purge+Suspend finch experiment
   // in the following way:
   // https://docs.google.com/document/d/1hPHkKtXXBTlsZx9s-9U17XC-ofEIzPo9FYbBEc7PPbk/edit?usp=sharing
   std::string purge_and_suspend_time = variations::GetVariationParamValue(
       "PurgeAndSuspend", "purge-and-suspend-time");
-  unsigned time_to_first_suspension_sec;
+  unsigned int time_to_first_purge_sec = 0;
   if (purge_and_suspend_time.empty() ||
-      !base::StringToUint(purge_and_suspend_time,
-                          &time_to_first_suspension_sec))
-    time_to_first_suspension_sec = 108000;
-  time_to_first_suspension_ =
-      base::TimeDelta::FromSeconds(time_to_first_suspension_sec);
+      !base::StringToUint(purge_and_suspend_time, &time_to_first_purge_sec))
+    time_to_first_suspension_ = kDefaultTimeToFirstPurge;
+  else
+    time_to_first_suspension_ =
+        base::TimeDelta::FromSeconds(time_to_first_purge_sec);
 }
 
 void TabManager::Stop() {
   update_timer_.Stop();
   recent_tab_discard_timer_.Stop();
   memory_pressure_listener_.reset();
 }
 
 TabStatsList TabManager::GetTabStats() const {
   TabStatsList stats_list(GetUnsortedTabStats());
@@ skipping 784 matching lines @@
   // platform.
   std::string allow_multiple_discards = variations::GetVariationParamValue(
       features::kAutomaticTabDiscarding.name, "AllowMultipleDiscards");
   return (allow_multiple_discards != "true");
 #else
   return false;
 #endif
 }
 
 }  // namespace memory