Make Sber1/2 pref metrics into Nullable Booleans so we can track how often these prefs are unset.

chrome/browser/profiles/profile.cc

 // Copyright (c) 2012 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/profiles/profile.h"
 
 #include <string>
 
 #include "build/build_config.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 82 matching lines @@
                               PrefRegistry::LOSSY_PREF);
   registry->RegisterBooleanPref(
       prefs::kSafeBrowsingEnabled,
       true,
       user_prefs::PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterBooleanPref(prefs::kSafeBrowsingExtendedReportingEnabled,
                                 false);
   registry->RegisterBooleanPref(prefs::kSafeBrowsingScoutReportingEnabled,
                                 false);
   registry->RegisterBooleanPref(prefs::kSafeBrowsingScoutGroupSelected, false);
+  registry->RegisterBooleanPref(
+      prefs::kSafeBrowsingSawInterstitialExtendedReporting, false);
+  registry->RegisterBooleanPref(
+      prefs::kSafeBrowsingSawInterstitialScoutReporting, false);
   registry->RegisterBooleanPref(prefs::kSafeBrowsingProceedAnywayDisabled,
                                 false);
   registry->RegisterBooleanPref(prefs::kSSLErrorOverrideAllowed, true);
   registry->RegisterDictionaryPref(prefs::kSafeBrowsingIncidentsSent);
   registry->RegisterBooleanPref(
       prefs::kSafeBrowsingExtendedReportingOptInAllowed, true);
   // This pref is intentionally outside the above #if. That flag corresponds
   // to the Notifier extension and does not gate the launcher page.
   // TODO(skare): Remove or rename ENABLE_GOOGLE_NOW: http://crbug.com/459827.
   registry->RegisterBooleanPref(prefs::kGoogleNowLauncherEnabled, true);
@@ skipping 129 matching lines @@
   if (a->IsSameProfile(b))
     return false;
   return a->GetOriginalProfile() < b->GetOriginalProfile();
 }
 
 double Profile::GetDefaultZoomLevelForProfile() {
   return GetDefaultStoragePartition(this)
       ->GetHostZoomMap()
       ->GetDefaultZoomLevel();
 }