Construct the site engagement helper with a site engagement service.

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 "chrome/browser/engagement/site_engagement_service.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
 namespace content {
 class NavigationHandle;
 class WebContents;
 }
 
 // Per-WebContents class to handle updating the site engagement scores for
 // origins.
 class SiteEngagementService::Helper
     : public content::WebContentsObserver,
       public content::WebContentsUserData<SiteEngagementService::Helper> {
  public:
   ~Helper() override;
 
+  static void CreateForWebContents(content::WebContents* web_contents,
+                                   SiteEngagementService* service);
   static void SetSecondsBetweenUserInputCheck(int seconds);
   static void SetSecondsTrackingDelayAfterNavigation(int seconds);
   static void SetSecondsTrackingDelayAfterShow(int seconds);
 
  private:
   // Class to encapsulate the periodic detection of site engagement.
   //
   // Engagement detection begins at some constant time delta following
   // navigation, tab activation, or media starting to play. Once engagement is
   // recorded, detection is suspended for another constant time delta. For sites
@@ skipping 101 matching lines @@
     void MediaStoppedPlaying(const MediaPlayerId& id) override;
     void WasShown() override;
     void WasHidden() override;
 
     bool is_hidden_;
     std::vector<MediaPlayerId> active_media_players_;
 
     DISALLOW_COPY_AND_ASSIGN(MediaTracker);
   };
 
-  explicit Helper(content::WebContents* web_contents);
+  Helper(content::WebContents* web_contents, SiteEngagementService* service);
   friend class content::WebContentsUserData<SiteEngagementService::Helper>;
   friend class SiteEngagementHelperTest;
 
   // Ask the SiteEngagementService to record engagement via user input at the
   // current WebContents URL.
   void RecordUserInput(SiteEngagementMetrics::EngagementType type);
 
   // Ask the SiteEngagementService to record engagement via media playing at the
   // current WebContents URL.
   void RecordMediaPlaying(bool is_hidden);
 
   // content::WebContentsObserver overrides.
   void DidFinishNavigation(content::NavigationHandle* handle) override;
   void WasShown() override;
   void WasHidden() override;
 
   InputTracker input_tracker_;
   MediaTracker media_tracker_;
+  SiteEngagementService* service_;
   bool record_engagement_;
 
   DISALLOW_COPY_AND_ASSIGN(Helper);
 };
 
 #endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_HELPER_H_