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

content/test/mock_render_thread.h

Index: content/test/mock_render_thread.h
diff --git a/content/test/mock_render_thread.h b/content/test/mock_render_thread.h
index 4223ab2ac03c724ca819d8db717f98bd63d610d7..0ad5018866f6b03e5caa46476f1650dc43ec9058 100644
--- a/content/test/mock_render_thread.h
+++ b/content/test/mock_render_thread.h
@@ -61,6 +61,7 @@ class MockRenderThread : 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;