Purge memory before suspending timer queues when backgrounded.

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index 1506ecf06f0346a10c7415cde00d725604a34303..910c9fd559ff915485fdda6c5aeb56fec6cc9c47 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -517,6 +517,9 @@ class CONTENT_EXPORT RenderThreadImpl
   void RecordAction(const base::UserMetricsAction& action) override;
   void RecordComputedAction(const std::string& action) override;
 
+  void PurgeBeforeSuspendTimerQueue();
+  void SuspendTimerQueueWhenBackgrounded();
+
   bool IsMainThread();
 
   // base::MemoryCoordinatorClient implementation:
@@ -763,6 +766,14 @@ class CONTENT_EXPORT RenderThreadImpl
   scoped_refptr<mojom::ThreadSafeRenderMessageFilterAssociatedPtr>
       thread_safe_render_message_filter_;
 
+  // The amount of time to wait before suspending shared timers after the
+  // renderer has been backgrounded. This is used only if background suspension
+  // of shared timers is enabled.
+  static const int kSuspendTimersWhenBackgroundedDelayMillis = 5 * 60 * 1000;
+
+  base::CancelableClosure purge_before_suspend_timers_closure_;
+  base::CancelableClosure suspend_timers_when_backgrounded_closure_;
+
   base::CancelableClosure record_purge_suspend_metric_closure_;
   RendererMemoryMetrics purge_and_suspend_memory_metrics_;
   base::CancelableClosure record_purge_suspend_growth_metric_closure_;