Add a delay to Site Engagement tracking after navigation.

chrome/browser/engagement/site_engagement_helper.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_HELPER_H_
 #define CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_HELPER_H_
 
 #include "base/macros.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/engagement/site_engagement_metrics.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 namespace content {
 class WebContents;
 }
 
 class GURL;
 
 // Per-WebContents class to handle updating the site engagement scores for
 // origins.
 class SiteEngagementHelper
     : public content::WebContentsObserver,
       public content::WebContentsUserData<SiteEngagementHelper> {
  public:
   ~SiteEngagementHelper() override;
 
-  static void SetSecondsBetweenUserInputCheck(double seconds);
+  static void SetSecondsBetweenUserInputCheck(int seconds);
+  static void SetSecondsTrackingDelayAfterNavigation(int seconds);
+  static void SetSecondsTrackingDelayAfterShow(int seconds);
 
  private:
   // Class to encapsulate the user input listening.
   //
   // Time on site is recorded by detecting any user input (mouse or keypress)
   // per some discrete time unit. If there is user input, then record a positive
   // site engagement.
   //
   // When input is detected, SiteEngagementHelper::RecordUserInput is called,
   // and the input detection callbacks are paused for
   // g_seconds_between_user_input_check. This ensures that there is minimal
   // overhead in input listening, and that input over an extended length of time
   // is required to continually increase the engagement score.
   class InputTracker {
    public:
     explicit InputTracker(SiteEngagementHelper* helper);
     ~InputTracker();
 
     // Callback to handle key press events from the RenderViewHost.
     bool HandleKeyPressEvent(const content::NativeWebKeyboardEvent& event);
 
     // Callback to handle mouse events from the RenderViewHost.
     bool HandleMouseEvent(const blink::WebMouseEvent& event);
 
     // Register callbacks to listen for user input.
-    void StartTracking(content::RenderViewHost* host);
+    void StartTracking(content::RenderViewHost* host,
+                       base::TimeDelta initial_delay);
 
-    // Pause listening for user input, restarting listening after
-    // g_seconds_between_user_input_check seconds.
-    void PauseTracking(content::RenderViewHost* host);
+    // Pause listening for user input, restarting listening after a delay.
+    void PauseTracking();
 
-    // Restart listening for user input.
-    void ResumeTracking();
+    void SwitchRenderViewHost(content::RenderViewHost* new_host);
 
     // Stop listening for user input.
-    void StopTracking(content::RenderViewHost* host);
+    void StopTracking();
+
+    // Returns whether the InputTracker has been started for a RenderViewHost.
+    bool is_tracking() const { return is_tracking_; }
+
+    // Returns whether input tracking callbacks have been added to
+    // RenderViewHost.
+    bool callbacks_added() const { return callbacks_added_; }
 
     // Set the timer object for testing purposes.
-    void SetTimerForTesting(scoped_ptr<base::Timer> timer);
-
-    bool callbacks_added() { return callbacks_added_; }
+    void SetPauseTimerForTesting(scoped_ptr<base::Timer> timer);
 
    private:
+    // Starts the timer for adding callbacks to the RenderViewHost.
+    void StartTimer(base::TimeDelta delay);
+
+    // Adds/removes tracking callbacks to the RenderViewHost.
+    void AddCallbacks();
+    void RemoveCallbacks();
+
     SiteEngagementHelper* helper_;
     scoped_ptr<base::Timer> pause_timer_;
+    content::RenderViewHost* host_;
     content::RenderWidgetHost::KeyPressEventCallback key_press_event_callback_;
     content::RenderWidgetHost::MouseEventCallback mouse_event_callback_;
+    bool is_tracking_;
     bool callbacks_added_;
   };
 
   explicit SiteEngagementHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<SiteEngagementHelper>;
   friend class SiteEngagementServiceBrowserTest;
 
   // Ask the SiteEngagementService to record engagement via user input at the
   // current contents location.
   void RecordUserInput(SiteEngagementMetrics::EngagementType type);
 
-  bool ShouldRecordEngagement();
-
   // content::WebContentsObserver overrides.
   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;
 
   InputTracker input_tracker_;
   bool record_engagement_;
 
   DISALLOW_COPY_AND_ASSIGN(SiteEngagementHelper);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_HELPER_H_