Enable site engagement in incognito.

chrome/browser/engagement/site_engagement_service_factory.cc

Index: chrome/browser/engagement/site_engagement_service_factory.cc
diff --git a/chrome/browser/engagement/site_engagement_service_factory.cc b/chrome/browser/engagement/site_engagement_service_factory.cc
index 783883657ca4532a65957f1d24bdfbdde68bd8f3..347facefca6f6b42ab9bf33ce851f4897e1851fd 100644
--- a/chrome/browser/engagement/site_engagement_service_factory.cc
+++ b/chrome/browser/engagement/site_engagement_service_factory.cc
@@ -7,6 +7,7 @@
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
 #include "chrome/browser/engagement/site_engagement_service.h"
 #include "chrome/browser/history/history_service_factory.h"
+#include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 
@@ -41,3 +42,8 @@ KeyedService* SiteEngagementServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new SiteEngagementService(static_cast<Profile*>(profile));
 }
+
+content::BrowserContext* SiteEngagementServiceFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  return chrome::GetBrowserContextOwnInstanceInIncognito(context);
+}