Add a delay to Site Engagement tracking after navigation.

chrome/browser/engagement/site_engagement_helper.h

Index: chrome/browser/engagement/site_engagement_helper.h
diff --git a/chrome/browser/engagement/site_engagement_helper.h b/chrome/browser/engagement/site_engagement_helper.h
index af059d431b24d98915c81add6e339156697d6519..4d49d8a31908e350779bc15c6639cd6230168c23 100644
--- a/chrome/browser/engagement/site_engagement_helper.h
+++ b/chrome/browser/engagement/site_engagement_helper.h
@@ -63,10 +63,11 @@ class SiteEngagementHelper
     // Stop listening for user input.
     void StopTracking(content::RenderViewHost* host);
 
-    // Set the timer object for testing purposes.
-    void SetTimerForTesting(scoped_ptr<base::Timer> timer);
+    // Returns whether a RenderViewHost is being tracked.
+    bool IsTracking();
 
-    bool callbacks_added() { return callbacks_added_; }
+    // Set the timer object for testing purposes.
+    void SetPauseTimerForTesting(scoped_ptr<base::Timer> timer);
 
    private:
     SiteEngagementHelper* helper_;
@@ -90,15 +91,19 @@ class SiteEngagementHelper
   void DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) override;
-
   void RenderViewHostChanged(content::RenderViewHost* old_host,
                              content::RenderViewHost* new_host) override;
-
   void WasShown() override;
   void WasHidden() override;
 
+  // Set the timer object for testing purposes.
+  void SetNavigationTimerForTesting(scoped_ptr<base::Timer> timer);
+  void OnNavigationTimerFired();
+
+  scoped_ptr<base::Timer> navigation_timer_;
   InputTracker input_tracker_;
   bool record_engagement_;
+  bool visible_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementHelper);
 };