Construct the site engagement helper with a site engagement service.

chrome/browser/engagement/site_engagement_helper.cc

 // 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.
 
 #include "chrome/browser/engagement/site_engagement_helper.h"
 
 #include <utility>
 
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 144 matching lines @@
   is_hidden_ = true;
 }
 
 SiteEngagementService::Helper::~Helper() {
   if (web_contents()) {
     input_tracker_.Stop();
     media_tracker_.Stop();
   }
 }
 
-SiteEngagementService::Helper::Helper(content::WebContents* web_contents)
+SiteEngagementService::Helper::Helper(content::WebContents* web_contents,
+                                      SiteEngagementService* service)
     : content::WebContentsObserver(web_contents),
       input_tracker_(this, web_contents),
       media_tracker_(this, web_contents),
+      service_(service),

[calamity, 2016/06/09 01:41:19]

Can we use the web_contents->browser_context() to get the service here instead?

[dominickn, 2016/06/09 03:25:47]

Done.

       record_engagement_(false) {}
 
 void SiteEngagementService::Helper::RecordUserInput(
     SiteEngagementMetrics::EngagementType type) {
   TRACE_EVENT0("SiteEngagement", "RecordUserInput");
   content::WebContents* contents = web_contents();
-  if (contents) {
-    Profile* profile =
-        Profile::FromBrowserContext(contents->GetBrowserContext());
-    SiteEngagementService* service = SiteEngagementService::Get(profile);
-
-    // Service is null in incognito.
-    if (service)
-      service->HandleUserInput(contents->GetVisibleURL(), type);
-  }
+  // Service is null in incognito.
+  if (contents && service_)
+    service_->HandleUserInput(contents, type);
 }
 
 void SiteEngagementService::Helper::RecordMediaPlaying(bool is_hidden) {
   content::WebContents* contents = web_contents();
-  if (contents) {
-    Profile* profile =
-        Profile::FromBrowserContext(contents->GetBrowserContext());
-    SiteEngagementService* service = SiteEngagementService::Get(profile);
-
-    if (service)
-      service->HandleMediaPlaying(contents->GetVisibleURL(), is_hidden);
-  }
+  if (contents && service_)
+    service_->HandleMediaPlaying(contents, is_hidden);
 }
 
 void SiteEngagementService::Helper::DidFinishNavigation(
     content::NavigationHandle* handle) {
   input_tracker_.Stop();
   media_tracker_.Stop();
 
   // Ignore all schemes except HTTP and HTTPS, as well as uncommitted, non
   // main-frame, same page, or error page navigations.
   record_engagement_ = handle->GetURL().SchemeIsHTTPOrHTTPS();
@@ skipping 11 matching lines @@
   //   engagement.
   // - Prerenders initiated by <link rel="prerender"> (e.g. search results) are
   //   always assigned the LINK transition, which is ignored for navigation
   //   engagement.
   //
   // Prerenders trigger WasShown() when they are swapped in, so input engagement
   // will activate even if navigation engagement is not scored.
   if (prerender::PrerenderContents::FromWebContents(web_contents()) != nullptr)
     return;
 
-  Profile* profile =
-      Profile::FromBrowserContext(web_contents()->GetBrowserContext());
-  SiteEngagementService* service = SiteEngagementService::Get(profile);
-
-  if (service)
-    service->HandleNavigation(handle->GetURL(), handle->GetPageTransition());
+  if (service_)
+    service_->HandleNavigation(web_contents(), handle->GetPageTransition());
 
   input_tracker_.Start(
       base::TimeDelta::FromSeconds(g_seconds_delay_after_navigation));
 }
 
 void SiteEngagementService::Helper::WasShown() {
   // Ensure that the input callbacks are registered when we come into view.
   if (record_engagement_) {
     input_tracker_.Start(
         base::TimeDelta::FromSeconds(g_seconds_delay_after_show));
   }
 }
 
 void SiteEngagementService::Helper::WasHidden() {
   // Ensure that the input callbacks are not registered when hidden.
   input_tracker_.Stop();
 }
 
 // static
+void SiteEngagementService::Helper::CreateForWebContents(
+    content::WebContents* web_contents,
+    SiteEngagementService* service) {
+  DCHECK(web_contents);
+  if (!FromWebContents(web_contents)) {
+    web_contents->SetUserData(UserDataKey(), new SiteEngagementService::Helper(
+                                                 web_contents, service));
+  }
+}
+
+// static
 void SiteEngagementService::Helper::SetSecondsBetweenUserInputCheck(
     int seconds) {
   g_seconds_to_pause_engagement_detection = seconds;
 }
 
 // static
 void SiteEngagementService::Helper::SetSecondsTrackingDelayAfterNavigation(
     int seconds) {
   g_seconds_delay_after_navigation = seconds;
 }
 
 // static
 void SiteEngagementService::Helper::SetSecondsTrackingDelayAfterShow(
     int seconds) {
   g_seconds_delay_after_show = seconds;
 }