Use title case for verbose "Not Secure" omnibox state on Mac.

components/omnibox_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <grit-part>
 
   <message name="IDS_AUTOCOMPLETE_SEARCH_DESCRIPTION" desc="Description for the default search match.">
     <ph name="ENGINE">$1<ex>Google</ex></ph> Search
   </message>
   <message name="IDS_EMPTY_KEYWORD_VALUE" desc="Shown in the location bar drop down when the user enters a string that matches a chrome keyword, but they haven't entered any text following the chrome keyword">
     &lt;Type search term&gt;
   </message>
   <message name="IDS_LINK_FROM_CLIPBOARD" desc="The label in the omnibox dropdown explaining that the link has been extracted from the user's clipboard. [Length: 21em]">
     Link you copied
   </message>
   <message name="IDS_SECURE_CONNECTION_EV" desc="Short text shown in the location bar when the connection is secure with an EV cert.">
     <ph name="ORGANIZATION">$1<ex>Paypal Inc.</ex></ph> [<ph name="COUNTRY">$2<ex>US</ex></ph>]
   </message>
 
   <message name="IDS_SECURE_VERBOSE_STATE" desc="An adjective or short adjective phrase shown next to the green lock icon in the omnibox to describe a secure site (valid HTTPS connection). Note that 'secure' in this case primarily refers to HTTPS connection security, so prefer translations with a connotation of 'private' (no one can intercept your communication with the site) rather than 'trustworthy' (which would be a judgment of site reputation). This phrase takes away space from the URL in the omnibox, so it should ideally be as short as possible while staying accurate. This phrase should also make sense compared to the companion phrase 'Not Secure'." meaning="Omnibox phrase to describe a secure site.">
     Secure
   </message>
-  <message name="IDS_NOT_SECURE_VERBOSE_STATE" desc="An adjective or short adjective phrase shown next to the security indicator icon in the omnibox to describe a site that is not secure (unencrypted HTTP or invalid HTTPS connection). Note that 'not secure' in this case primarily refers to HTTPS connection security, so prefer translations with a connotation of 'not private' (someone can intercept your communication with the site) rather than 'not trustworthy' (which would be a judgment of site reputation). This phrase takes away space from the URL in the omnibox, so it should ideally be as short as possible while staying accurate. This phrase should also make sense compared to the companion phrase 'Secure'." meaning="Omnibox phrase to describe a site that is not secure.">
-    Not Secure
-  </message>
+  <if expr="not use_titlecase">
+    <message name="IDS_NOT_SECURE_VERBOSE_STATE" desc="An adjective or short adjective phrase shown next to the security indicator icon in the omnibox to describe a site that is not secure (unencrypted HTTP or invalid HTTPS connection). Note that 'not secure' in this case primarily refers to HTTPS connection security, so prefer translations with a connotation of 'not private' (someone can intercept your communication with the site) rather than 'not trustworthy' (which would be a judgment of site reputation). This phrase takes away space from the URL in the omnibox, so it should ideally be as short as possible while staying accurate. This phrase should also make sense compared to the companion phrase 'Secure'." meaning="Omnibox phrase to describe a site that is not secure.">
+      Not secure
+    </message>
+  </if>
+  <if expr="use_titlecase">
+    <message name="IDS_NOT_SECURE_VERBOSE_STATE" desc="An adjective or short adjective phrase shown next to the security indicator icon in the omnibox to describe a site that is not secure (unencrypted HTTP or invalid HTTPS connection). Note that 'not secure' in this case primarily refers to HTTPS connection security, so prefer translations with a connotation of 'not private' (someone can intercept your communication with the site) rather than 'not trustworthy' (which would be a judgment of site reputation). This phrase takes away space from the URL in the omnibox, so it should ideally be as short as possible while staying accurate. This phrase should also make sense compared to the companion phrase 'Secure'." meaning="Omnibox phrase to describe a site that is not secure.">
+      Not Secure
+    </message>
+  </if>
   <message name="IDS_DANGEROUS_VERBOSE_STATE" desc="Text for the Dangerous Omnibox Verbose State. Displayed when the current page fails the malware check.">
     Dangerous
   </message>
   <if expr="is_ios">
     <message name="IDS_OMNIBOX_EMPTY_HINT" desc="The text displayed in the omnibox when it is empty.">
       Search or type URL
     </message>
   </if>
   <message name="IDS_PHYSICAL_WEB_OVERFLOW_DESCRIPTION" desc="The description in the omnibox dropdown indicating that multiple nearby devices are broadcasting URLs.">
     Physical Web suggestions
   </message>
   <message name="IDS_PHYSICAL_WEB_OVERFLOW" desc="A label in the omnibox dropdown indicating the number of additional nearby devices broadcasting URLs.">
     {URL_count, plural, =1 {and 1 more web page} other {and # more web pages}}
   </message>
   <message name="IDS_PHYSICAL_WEB_OVERFLOW_EMPTY_TITLE" desc="A label in the omnibox dropdown indicating the number of additional nearby devices broadcasting URLs. This version is used when the title of the top result is empty.">
     {URL_count, plural, =1 {1 web page nearby} other {# web pages nearby}}
   </message>
 </grit-part>