memory_coordinator: Discard tabs under critical memory condition

content/browser/memory/memory_coordinator_impl.h

Index: content/browser/memory/memory_coordinator_impl.h
diff --git a/content/browser/memory/memory_coordinator_impl.h b/content/browser/memory/memory_coordinator_impl.h
index 4b63fb4cc38d88fafcf566aba4e8a951b7e1c36e..f22767be172e94f6060a1a4597acbf094290388e 100644
--- a/content/browser/memory/memory_coordinator_impl.h
+++ b/content/browser/memory/memory_coordinator_impl.h
@@ -108,9 +108,6 @@ class CONTENT_EXPORT MemoryCoordinatorImpl : public base::MemoryCoordinator,
   // like purging memory and memory state changes.
   void UpdateConditionIfNeeded(MemoryCondition condition);
 
-  // Asks the delegate to discard a tab.
-  void DiscardTab();
-
  protected:
   // Returns the RenderProcessHost which is correspond to the given id.
   // Returns nullptr if there is no corresponding RenderProcessHost.
@@ -193,11 +190,17 @@ class CONTENT_EXPORT MemoryCoordinatorImpl : public base::MemoryCoordinator,
   // Notifies a state change to child processes.
   void NotifyStateToChildren(MemoryState state);
 
+  // Asks the delegate to discard a tab.
+  void DiscardTab();
+
   std::unique_ptr<MemoryCoordinatorDelegate> delegate_;
   std::unique_ptr<MemoryMonitor> memory_monitor_;
   std::unique_ptr<MemoryConditionObserver> condition_observer_;
   NotificationRegistrar notification_registrar_;
 
+  base::Closure tab_discarding_closure_;
+  base::TimeDelta tab_discarding_interval_;
+
   // The current memory condition.
   MemoryCondition memory_condition_ = MemoryCondition::NORMAL;