About WebUI: change about section heading into h1 page heading

Bug: 870460
Change-Id: I0fa1762ca2f7054ab86116ce406b9acf9b8b37a7
Reviewed-on: https://chromium-review.googlesource.com/c/1311803Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604508}

chrome/browser/resources/settings/about_page/about_page.html

@@ -11,7 +11,9 @@
 <link rel="import" href="../settings_page/settings_section.html">
 <link rel="import" href="../settings_page_css.html">
 <link rel="import" href="../settings_shared_css.html">
+<link rel="import" href="../settings_vars_css.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
+<link rel="import" href="chrome://resources/cr_elements/shared_vars_css.html">
 <link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
@@ -37,6 +39,25 @@
         --about-page-image-space: 10px;
       }
 
+      settings-section[section='about'] {
+        --settings-section-header: {
+          display: none;
+        };
+      }
+
+      h1 {
+        color: var(--cr-primary-text-color);
+        font-size: 108%;
+        font-weight: 400;
+        letter-spacing: .25px;
+        margin-bottom: 12px;
+        margin-inline-end: 3px;
+        margin-inline-start: 3px;
+        margin-top: var(--settings-page-vertical-margin);
+        padding-bottom: 4px;
+        padding-top: 8px;
+      }
+
       .info-section {
         margin-bottom: 12px;
       }
@@ -87,6 +108,7 @@
       }
 </if>
     </style>
+    <h1>$i18n{aboutPageTitle}</h1>
     <div>
       <settings-section page-title="$i18n{aboutPageTitle}" section="about">
         <settings-animated-pages id="pages" section="about"

chrome/browser/resources/settings/settings_page/settings_section.html

@@ -19,6 +19,7 @@
 
       #header {
         margin-bottom: 12px;
+        @apply --settings-section-header;
       }
 
       #header .title {