Schedule idle handler in the foreground tab based on CPU usage and user activity.

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 e3fdac37a5c6174232a56b006338176ff29e7f88..70bd66b919307a9383b16c032f3c8f87ba0577c7 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -43,6 +43,7 @@ class WebStorageEventDispatcher;
 }
 
 namespace base {
+class ProcessMetrics;
 class MessageLoopProxy;
 class Thread;
 namespace win {
@@ -168,6 +169,11 @@ class CONTENT_EXPORT RenderThreadImpl : public content::RenderThread,
   // on the renderer's main thread.
   scoped_refptr<base::MessageLoopProxy> GetFileThreadMessageLoopProxy();
 
+  // Causes the idle handler to skip sending idle notifications
+  // on the two next scheduled calls, so idle notifications are
+  // not sent for at least one notification delay.
+  void PostponeIdleNotification();
+
  private:
   virtual bool OnControlMessageReceived(const IPC::Message& msg);
 
@@ -184,6 +190,8 @@ class CONTENT_EXPORT RenderThreadImpl : public content::RenderThread,
   void OnGetAccessibilityTree();
   void OnTempCrashWithData(const GURL& data);
 
+  void IdleHandlerInForegroundTab();
+
   // These objects live solely on the render thread.
   scoped_ptr<ScopedRunnableMethodFactory<RenderThreadImpl> > task_factory_;
   scoped_ptr<AppCacheDispatcher> appcache_dispatcher_;
@@ -218,12 +226,17 @@ class CONTENT_EXPORT RenderThreadImpl : public content::RenderThread,
   // The current value of the idle notification timer delay.
   int64 idle_notification_delay_in_ms_;
 
+  // The number of idle handler calls that skip sending idle notifications.
+  int idle_notifications_to_skip_;
+
   bool suspend_webkit_shared_timer_;
   bool notify_webkit_of_modal_loop_;
 
   // Timer that periodically calls IdleHandler.
   base::RepeatingTimer<RenderThreadImpl> idle_timer_;
 
+  scoped_ptr<base::ProcessMetrics> process_metrics_;
+
   // The channel from the renderer process to the GPU process.
   scoped_refptr<GpuChannelHost> gpu_channel_;