Update WebView manifest for API 24.

android_webview/apk/java/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--
   Copyright (c) 2012 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.
 -->
 
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     package="{{package|default('com.android.webview')}}">
     <uses-sdk android:minSdkVersion="{{minsdk|default(21)}}"
-              android:targetSdkVersion="{{targetsdk|default(23)}}">
+              android:targetSdkVersion="{{targetsdk|default(24)}}">
     </uses-sdk>
 
     <uses-feature android:name="android.hardware.touchscreen"
             android:required="false"/>
 
     <application android:label="Android System WebView"
         android:icon="@drawable/icon_webview"
         android:multiArch="true">
         {# This part is shared between stand-alone WebView and Monochrome #}
         {% macro common(manifest_package, webview_lib) %}
@@ skipping 12 matching lines @@
             <meta-data android:name="com.android.webview.WebViewLibrary"
                     android:value="{{ webview_lib }}" />
         {% endmacro %}
         {{ common(package|default('com.android.webview'), 'libwebviewchromium.so') }}
         <meta-data android:name="org.chromium.content.browser.NUM_SANDBOXED_SERVICES"
                    android:value="1"/>
         <service android:name="org.chromium.content.app.SandboxedProcessService0"
                  android:process=":sandboxed_process0"
                  android:isolatedProcess="true"
                  android:exported="true"
-                 tools:ignore="ExportedService"
-                 {{sandboxed_service_extra_flags|default('')}} />
+                 android:externalService="true"
+                 tools:ignore="ExportedService" />
         <meta-data android:name="org.chromium.content.browser.NUM_PRIVILEGED_SERVICES"
                    android:value="0"/>
     </application>
 </manifest>