MD Settings: Remove usage of deprecated iron-flex-layout.html.

chrome/browser/resources/settings/settings_main/settings_main.html

Index: chrome/browser/resources/settings/settings_main/settings_main.html
diff --git a/chrome/browser/resources/settings/settings_main/settings_main.html b/chrome/browser/resources/settings/settings_main/settings_main.html
index e20499dee9864f2378301a219134a40cc30d8b81..9eb0f6a9af0575b40fd2a5eb7086a31220b40fd2 100644
--- a/chrome/browser/resources/settings/settings_main/settings_main.html
+++ b/chrome/browser/resources/settings/settings_main/settings_main.html
@@ -1,3 +1,4 @@
+<link rel="import" href="chrome://resources/cr_elements/hidden_style_css.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/promise_resolver.html">
@@ -8,11 +9,12 @@
 <link rel="import" href="../basic_page/basic_page.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../route.html">
+<link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="../settings_vars_css.html">
 
 <dom-module id="settings-main">
   <template>
-    <style>
+    <style include="cr-hidden-style">
       #overscroll {
         margin-top: 64px;
       }