[Android] Update Protected Media Identifier Settings UI to reflect exceptions.

chrome/android/java/res/xml/website_preferences.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2015 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. -->
 
 <PreferenceScreen
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:chrome="http://schemas.android.com/apk/res-auto"
     android:title="@string/all_sites">
     <!-- A global toggle, only shown for specific categories that allow turning default values
          for that category on/off.-->
     <org.chromium.chrome.browser.preferences.ChromeSwitchPreference
         android:key="read_write_toggle"
         android:defaultValue="true"
         chrome:drawDivider="true" />
     <!-- A toggle for allowing third-party cookies, only shown for the Cookies category. -->
     <org.chromium.chrome.browser.preferences.ChromeBaseCheckBoxPreference
         android:key="third_party_cookies"
         android:title="@string/allow_third_party_cookies_title"
         android:summary="@string/allow_third_party_cookies_summary"
         android:defaultValue="true" />
+    <!-- An hyperlink to explain more about Protected Media content settings. -->
+    <org.chromium.chrome.browser.preferences.HyperlinkPreference
+        android:key="protected_content_learn_more"
+        android:title="@string/learn_more"
+        android:background="?android:attr/listDivider"
+        chrome:url="@string/protected_content_learn_more_url"
+        chrome:imitateWebLink="true" />
     <!-- Collapsible headers for sorting preferences. -->
     <org.chromium.chrome.browser.preferences.ExpandablePreferenceGroup
         android:key="blocked_group" />
     <org.chromium.chrome.browser.preferences.ExpandablePreferenceGroup
         android:key="allowed_group" />
 </PreferenceScreen>