Make purge-and-suspend-time finch experiment parameter

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 713 matching lines @@
       break;
     case SUSPENDED:
       if (time_passed > kDurationOfRendererSuspension)
         return RESUMED;
       break;
   }
   return state;
 }
 
 void TabManager::PurgeAndSuspendBackgroundedTabs() {
-  const base::CommandLine& command_line =
-      *base::CommandLine::ForCurrentProcess();
-  if (!command_line.HasSwitch(switches::kPurgeAndSuspendTime))
+  std::string purge_and_suspend_time = variations::GetVariationParamValue(

[chrisha, 2016/11/23 19:38:09]

Maybe do this once in some kind of initialization phase, and save the value to
the object? Rather than doing this on every call to
PurgeAndSuspendBackgroundedTabs?

[tasak, 2016/11/24 02:16:20]

I see. Done.

+      "PurgeAndSuspend", "purge-and-suspend-time");
+  int time_to_first_suspension_sec = 0;
+  if (purge_and_suspend_time.empty() ||
+      !base::StringToInt(purge_and_suspend_time, &time_to_first_suspension_sec))
     return;
-  int purge_and_suspend_time = 0;
-  if (!base::StringToInt(
-          command_line.GetSwitchValueASCII(switches::kPurgeAndSuspendTime),
-          &purge_and_suspend_time)) {
-    return;
-  }
-  if (purge_and_suspend_time <= 0)
+  if (time_to_first_suspension_sec <= 0)
     return;
   base::TimeTicks current_time = NowTicks();
   base::TimeDelta time_to_first_suspension =
-      base::TimeDelta::FromSeconds(purge_and_suspend_time);
+      base::TimeDelta::FromSeconds(time_to_first_suspension_sec);
   auto tab_stats = GetUnsortedTabStats();
   for (auto& tab : tab_stats) {
     if (!tab.render_process_host->IsProcessBackgrounded())
       continue;
     if (!CanSuspendBackgroundedRenderer(tab.child_process_host_id))
       continue;
 
     WebContents* content = GetWebContentsById(tab.tab_contents_id);
     if (!content)
       continue;
@@ skipping 271 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