MD Settings: Fix SiteDetails.DefaultSettingSource by using a secure test origin.

Certain permissions are always denied for insecure (HTTP) origins, and
notifications is one of them. Fix SiteDetails.DefaultSettingSource by using a
secure (HTTPS) test origin instead.

This is to fix a test that broke after r488086 landed.

Change-Id: Ieac59f3ff7b19dd64d0d299fb678ce7f6e9ec89e
TBR: dschuyler@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/578534
Commit-Queue: Patti <patricialor@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488133}

chrome/browser/ui/webui/settings/site_settings_handler_unittest.cc

@@ -357,7 +357,7 @@ TEST_F(SiteSettingsHandlerTest, Origins) {
 }
 
 TEST_F(SiteSettingsHandlerTest, DefaultSettingSource) {
-  const std::string google("http://www.google.com");
+  const std::string google("https://www.google.com");
   ContentSettingSourceSetter source_setter(profile(),
                                            CONTENT_SETTINGS_TYPE_NOTIFICATIONS);