Initialize all fields in WebsiteSettings.

show_ssl_decision_revoke_button_ field was never assigned when
constructing WebsiteSettings with about:blank url.

BUG=

Review-Url: https://codereview.chromium.org/2440183002
Cr-Commit-Position: refs/heads/master@{#427292}

chrome/browser/ui/website_settings/website_settings.cc

@@ -264,6 +264,7 @@ WebsiteSettings::WebsiteSettings(
       site_url_(url),
       site_identity_status_(SITE_IDENTITY_STATUS_UNKNOWN),
       site_connection_status_(SITE_CONNECTION_STATUS_UNKNOWN),
+      show_ssl_decision_revoke_button_(false),
       content_settings_(HostContentSettingsMapFactory::GetForProfile(profile)),
       chrome_ssl_host_state_delegate_(
           ChromeSSLHostStateDelegateFactory::GetForProfile(profile)),