Introduce AncestorThrottle, which will process 'X-Frame-Options' headers.

components/error_page_strings.grdp

Index: components/error_page_strings.grdp
diff --git a/components/error_page_strings.grdp b/components/error_page_strings.grdp
index 1d7ae2864971f4e84de1272b3aabb190fdf3992a..882ec181e11b407990a0c5ed300e07e8d3d40b86 100644
--- a/components/error_page_strings.grdp
+++ b/components/error_page_strings.grdp
@@ -455,6 +455,9 @@
   <message name="IDS_ERRORPAGES_SUMMARY_BLOCKED_BY_ADMINISTRATOR" desc="Summary in the error page when an administrator policy blocks a request.">
     The person who set up this computer has chosen to block this site.
   </message>
+  <message name="IDS_ERRORPAGES_SUMMARY_BLOCKED_BY_RESPONSE" desc="Summary in the error page when the response blocks itself.">
+    The page at this URL has requested not to be displayed in this context.
+  </message>
   <message name="IDS_ERRORPAGES_DETAILS_BLOCKED_BY_EXTENSION" desc="The error message displayed when an extension blocks a request.">
     Requests to the server have been blocked by an extension.
   </message>
@@ -465,6 +468,12 @@
     Browsing the Internet is disabled until the enterprise enrollment verification check has finished.
     You can still use the diagnostic tool presented here to troubleshoot issues with your connectivity.
   </message>
+  <message name="IDS_ERRORPAGES_DETAILS_BLOCKED_BY_RESPONSE" desc="Details in the error page when the response blocks itself.">
+    The server has chosen not to allow this page to be displayed in the current context by sending a
+    &lt;code&gt;X-Frame-Options&lt;/code&gt; header or a &lt;code&gt;Content-Security-Policy&lt;/code&gt;
+    header with a &lt;code&gt;frame-ancestors&lt;/code&gt; directive.
+  </message>
+
 
   <message name="IDS_ERRORPAGES_HTTP_POST_WARNING" desc="The error message displayed when the user navigates back or forward to a page which would resubmit post data. They can hit reload to send POST data again and load the page.">
     This webpage requires data that you entered earlier in order to be properly displayed. You can send this data again, but by doing so you will repeat any action this page previously performed.