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..61836dde3e342281ddbbe72642b698a9132a2a56 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 {
@@ -113,6 +114,7 @@ class CONTENT_EXPORT RenderThreadImpl : public content::RenderThread,
   virtual int64 GetIdleNotificationDelayInMs() const OVERRIDE;
   virtual void SetIdleNotificationDelayInMs(
       int64 idle_notification_delay_in_ms) OVERRIDE;
+  virtual void PostponeIdleNotification() OVERRIDE;
 #if defined(OS_WIN)
   virtual void PreCacheFont(const LOGFONT& log_font) OVERRIDE;
   virtual void ReleaseCachedFonts() OVERRIDE;
@@ -184,6 +186,8 @@ 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 +222,17 @@ 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_;