Fix up a few more lint warnings in chrome/

chrome/android/java/res/layout/website_settings_permission_row.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2014 The Chromium Authors. All rights reserved.
      Use of this source code is governed by a BSD-style license that can be
      found in the LICENSE file. -->
 
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:paddingTop="18dp" >
 
     <ImageView
         android:id="@+id/website_settings_permission_icon"
         android:layout_width="@dimen/website_settings_popup_permission_icon_size"
         android:layout_height="@dimen/website_settings_popup_permission_icon_size"
-        android:layout_marginEnd="16dp" />
+        android:layout_marginEnd="16dp"
+        android:contentDescription="@null" />
 
     <TextView
         android:id="@+id/website_settings_permission_name"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_toEndOf="@id/website_settings_permission_icon"
         android:textColor="#444444"
         android:textSize="14sp"
         android:textStyle="bold" />
 
     <Spinner
         android:id="@+id/website_settings_permission_spinner"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_toEndOf="@id/website_settings_permission_icon"
         android:layout_below="@id/website_settings_permission_name" />
 
     <View
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:layout_toEndOf="@id/website_settings_permission_icon"
         android:layout_below="@id/website_settings_permission_spinner"
         android:background="#e5e5e5" />
 
 </RelativeLayout>