Welcome: Hide logos from screen readers

Fixed: 1098542
Change-Id: I44d2ea06756939a4d60d533b90d40c57e9e09a4f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2318307Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791920}

chrome/browser/resources/welcome/google_apps/nux_google_apps.html

@@ -157,7 +157,7 @@
   }
 </style>
 <div class="apps-ask">
-  <div class="chrome-logo" alt=""></div>
+  <div class="chrome-logo" aria-hidden="true"></div>
   <h1 tabindex="-1">$i18n{googleAppsDescription}</h1>
   <div id="appChooser">
     <div class="slide-in">

chrome/browser/resources/welcome/ntp_background/nux_ntp_background.html

@@ -158,7 +158,7 @@
 </div>
 
 <div class="content">
-  <div class="ntp-background-logo"></div>
+  <div class="ntp-background-logo" aria-hidden="true"></div>
   <h1 tabindex="-1">$i18n{ntpBackgroundDescription}</h1>
 
   <div class="ntp-backgrounds-grid slide-in">

chrome/browser/resources/welcome/set_as_default/nux_set_as_default.html

@@ -65,7 +65,7 @@
 </if>
 </style>
 <div class="container">
-  <div class="logo"></div>
+  <div class="logo" aria-hidden="true"></div>
   <h1 tabindex="-1">$i18n{setDefaultHeader}</h1>
   <h2>$i18n{setDefaultSubHeader}</h2>
   <div class="illustration slide-in" aria-hidden="true"></div>