Remove obsolete SHA-1 UX elements

components/pageinfo_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <grit-part>
   <message name="IDS_PAGE_INFO_HELP_CENTER_LINK" desc="This is the text of the link pointing to the Help Center. This appears at the bottom of the SSL dialog and 'this' refers to the sections within the bubble.">
     What do these mean?
   </message>
-  <message name="IDS_PAGE_INFO_SECURITY_TAB_DEPRECATED_SIGNATURE_ALGORITHM_MINOR" desc="The security summary phrase in the page information panel for a security problem where the site's certificate expires in 2016 and contains a SHA1 signature in the chain (as opposed to 2017 or later). Such certificates will not be supported in a future version of Chrome.">
-    The certificate for this site expires in 2016, and the certificate chain contains a certificate signed using SHA-1.
-  </message>
-  <message name="IDS_PAGE_INFO_SECURITY_TAB_DEPRECATED_SIGNATURE_ALGORITHM_MAJOR" desc="The security summary phrase in the page information panel for a security problem where the site's certificate expires in 2017 or later and contains a SHA1 signature in the chain (as opposed to 2016). Such certificates will not be supported in a future version of Chrome.">
-    The certificate for this site expires in 2017 or later, and the certificate chain contains a certificate signed using SHA-1.
+  <message name="IDS_PAGE_INFO_SECURITY_TAB_DEPRECATED_SIGNATURE_ALGORITHM" desc="The security summary phrase in the page information panel for a security problem where the site's certificate chain contains a SHA1 signature. Such certificates are not supported except when a policy override is present.">

[estark, 2017/01/08 16:39:58]

optional nit: "not supported" => "treated as errors"
(not sure if that's actually better or not)

[elawrence, 2017/01/09 18:13:11]

Done.

+    The certificate chain for this site contains a certificate signed using SHA-1.
   </message>
   <message name="IDS_PAGE_INFO_SECURITY_TAB_ENCRYPTED_CONNECTION_TEXT" desc="The text of the connection section when the connection is encrypted.">
     Your connection to <ph name="DOMAIN">$1<ex>www.google.com</ex></ph> is encrypted using a modern cipher suite.
   </message>
   <message name="IDS_PAGE_INFO_SECURITY_TAB_ENCRYPTED_INSECURE_CONTENT_ERROR" desc="Some extra text of the connection section when the connection is encrypted and the page contains insecure content which has been run (e.g. script).">
     Further, this page includes other resources which are not secure. These resources can be viewed by others while in transit, and can be modified by an attacker to change the behavior of the page.
   </message>
   <message name="IDS_PAGE_INFO_SECURITY_TAB_ENCRYPTED_INSECURE_CONTENT_WARNING" desc="Some extra text of the connection section when the connection is encrypted and the page contains insecure content which has been displayed (e.g. images, CSS).">
     Further, this page includes other resources which are not secure. These resources can be viewed by others while in transit, and can be modified by an attacker to change the look of the page.
   </message>
@@ skipping 44 matching lines @@
     <message name="IDS_PAGEINFO_CERT_INFO_BUTTON" desc="Text of button in the page info that shows the SSL certificate.">
       Certificate information
     </message>
   </if>
   <if expr="use_titlecase">
     <message name="IDS_PAGEINFO_CERT_INFO_BUTTON" desc="In Title Case: Text of button in the page info that shows the SSL certificate.">
       Certificate Information
     </message>
   </if>
 </grit-part>