Add type for testing to interstitials.

chrome/browser/supervised_user/supervised_user_interstitial.cc

Index: chrome/browser/supervised_user/supervised_user_interstitial.cc
diff --git a/chrome/browser/supervised_user/supervised_user_interstitial.cc b/chrome/browser/supervised_user/supervised_user_interstitial.cc
index 65798dc6028cf02d1800be33eee4cae5c1094fb0..c9d8ae086ef22f07b744e49564305982f68d970f 100644
--- a/chrome/browser/supervised_user/supervised_user_interstitial.cc
+++ b/chrome/browser/supervised_user/supervised_user_interstitial.cc
@@ -99,6 +99,10 @@ class TabCloser : public content::WebContentsUserData<TabCloser> {
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(TabCloser);
 
+content::InterstitialPageDelegate::TypeID
+    SupervisedUserInterstitial::kTypeForTesting =
+        &SupervisedUserInterstitial::kTypeForTesting;
+
 // static
 void SupervisedUserInterstitial::Show(
     WebContents* web_contents,
@@ -114,6 +118,11 @@ void SupervisedUserInterstitial::Show(
   // Otherwise |interstitial_page_| is responsible for deleting it.
 }
 
+content::InterstitialPageDelegate::TypeID
+SupervisedUserInterstitial::GetTypeForTesting() const {
+  return SupervisedUserInterstitial::kTypeForTesting;
+}
+
 SupervisedUserInterstitial::SupervisedUserInterstitial(
     WebContents* web_contents,
     const GURL& url,