Add learn more link to Crostini Settings page

Bug: 862609
Change-Id: I27594afaa4b128ff0ae8e6009ff5c88eb22c69f3
Reviewed-on: https://chromium-review.googlesource.com/1160123Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Renée Wright <rjwright@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580410}

chrome/app/settings_strings.grdp

@@ -438,7 +438,7 @@
       Linux
     </message>
     <message name="IDS_SETTINGS_CROSTINI_SUBTEXT" desc="Description for the section for enabling and managing Crostini.">
-      Run Linux tools, editors, and IDEs on your Chromebook.
+      Run Linux tools, editors, and IDEs on your Chromebook. &lt;a target="_blank" href="<ph name="URL">$1<ex>https://google.com/</ex></ph>"&gt;Learn more&lt;/a&gt;
     </message>
     <message name="IDS_SETTINGS_CROSTINI_REMOVE" desc="Label for the row to open a dialog confirming removal of Crostini.">
       Remove Linux Apps for Chromebook

chrome/browser/resources/settings/crostini_page/crostini_page.html

@@ -24,8 +24,8 @@
             on-click="onSubpageTap_">
           <div class="start">
             $i18n{crostiniPageLabel}
-            <div class="secondary" id="secondaryText">
-                $i18n{crostiniSubtext}
+            <div class="secondary" id="secondaryText"
+                inner-h-t-m-l="[[i18nAdvanced('crostiniSubtext')]]">
             </div>
           </div>
           <cr-policy-pref-indicator pref="[[prefs.crostini.enabled]]"

chrome/browser/resources/settings/crostini_page/crostini_page.js

@@ -12,7 +12,7 @@
 Polymer({
   is: 'settings-crostini-page',
 
-  behaviors: [PrefsBehavior],
+  behaviors: [I18nBehavior, PrefsBehavior],
 
   properties: {
     /** Preferences state. */

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

@@ -394,13 +394,17 @@ void AddAboutStrings(content::WebUIDataSource* html_source) {
 void AddCrostiniStrings(content::WebUIDataSource* html_source) {
   LocalizedString localized_strings[] = {
       {"crostiniPageTitle", IDS_SETTINGS_CROSTINI_TITLE},
-      {"crostiniSubtext", IDS_SETTINGS_CROSTINI_SUBTEXT},
       {"crostiniPageLabel", IDS_SETTINGS_CROSTINI_LABEL},
       {"crostiniEnable", IDS_SETTINGS_TURN_ON},
       {"crostiniRemove", IDS_SETTINGS_CROSTINI_REMOVE},
   };
   AddLocalizedStringsBulk(html_source, localized_strings,
                           arraysize(localized_strings));
+  html_source->AddString(
+      "crostiniSubtext",
+      l10n_util::GetStringFUTF16(
+          IDS_SETTINGS_CROSTINI_SUBTEXT,
+          GetHelpUrlWithBoard(chrome::kLinuxAppsLearnMoreURL)));
 }
 
 void AddAndroidAppStrings(content::WebUIDataSource* html_source) {