Purge once random minutes(between 30min and 60min) after backgrounded.

chrome/browser/memory/tab_manager_web_contents_data.cc

Index: chrome/browser/memory/tab_manager_web_contents_data.cc
diff --git a/chrome/browser/memory/tab_manager_web_contents_data.cc b/chrome/browser/memory/tab_manager_web_contents_data.cc
index 92ebc887cf0a8566ac907b3f32d449f356dc62d6..b5851677eca5fa2f810302115ca4c99cc9995884 100644
--- a/chrome/browser/memory/tab_manager_web_contents_data.cc
+++ b/chrome/browser/memory/tab_manager_web_contents_data.cc
@@ -22,9 +22,8 @@ namespace memory {
 TabManager::WebContentsData::WebContentsData(content::WebContents* web_contents)
     : WebContentsObserver(web_contents),
       test_tick_clock_(nullptr),
-      last_purge_and_suspend_modified_time_(
-          base::TimeTicks::FromInternalValue(0)),
-      purge_and_suspend_state_(RUNNING) {}
+      time_to_purge_(base::TimeDelta::FromMinutes(30)),
+      is_purged_(false) {}
 
 TabManager::WebContentsData::~WebContentsData() {}
 
@@ -202,25 +201,4 @@ bool TabManager::WebContentsData::IsAutoDiscardable() {
   return tab_data_.is_auto_discardable;
 }
 
-void TabManager::WebContentsData::SetPurgeAndSuspendState(
-    PurgeAndSuspendState state) {
-  last_purge_and_suspend_modified_time_ = NowTicks();
-  purge_and_suspend_state_ = state;
-}
-
-base::TimeTicks TabManager::WebContentsData::LastPurgeAndSuspendModifiedTime()
-    const {
-  return last_purge_and_suspend_modified_time_;
-}
-
-void TabManager::WebContentsData::SetLastPurgeAndSuspendModifiedTimeForTesting(
-    base::TimeTicks timestamp) {
-  last_purge_and_suspend_modified_time_ = timestamp;
-}
-
-TabManager::PurgeAndSuspendState
-TabManager::WebContentsData::GetPurgeAndSuspendState() const {
-  return purge_and_suspend_state_;
-}
-
 }  // namespace memory