Settings: Serve Polymer 3 port from chrome://settings/settings_v3.html.

Previously this was happening for optimize_webui=false only. Changed
it to happen also for optimize_webui=true case.

Bug: 1026426
Change-Id: Icb8610e5aafc69e03510b575ec4700a9f9228d4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2037074
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738317}

chrome/browser/resources/settings/settings_resources_vulcanized.grd

@@ -39,6 +39,10 @@
                type="BINDATA"
                compress="gzip" />
       <!-- Polymer 3 related files -->
+      <include name="IDR_SETTINGS_SETTINGS_V3_HTML"
+               file="settings_v3.html"
+               type="BINDATA"
+               compress="gzip" />
       <include name="IDR_SETTINGS_SETTINGS_ROLLUP_JS"
                file="${root_gen_dir}\chrome\browser\resources\settings\settings.rollup.js"
                use_base_dir="false"

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

@@ -299,6 +299,8 @@ SettingsUI::SettingsUI(content::WebUI* web_ui)
 
   // Only used in Polymer 3, see https://crbug.com/1026426.
   html_source->AddResourcePath("settings.js", IDR_SETTINGS_SETTINGS_ROLLUP_JS);
+  html_source->AddResourcePath("settings_v3.html",
+                               IDR_SETTINGS_SETTINGS_V3_HTML);
 #else
   webui::SetupWebUIDataSource(
       html_source, base::make_span(kSettingsResources, kSettingsResourcesSize),