Update targetSdkVersion to 23.

android_webview/test/shell/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 
 <!-- Copyright 2013 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"
     package="org.chromium.android_webview.shell">
-  <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="21" />
+  <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="23" />
   <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
   <uses-permission android:name="android.permission.INTERNET"/>
   <uses-permission android:name="android.permission.WAKE_LOCK"/>
   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
   <uses-permission android:name="android.permission.RECORD_AUDIO" />
   <uses-permission android:name="android.permission.RECORD_VIDEO" />
   <uses-permission android:name="android.permission.CAMERA" />
 
   <application android:name="org.chromium.android_webview.shell.AwShellApplication"
       android:label="AwShellApplication"
@@ skipping 10 matching lines @@
         android:label="AwTestRunnerActivity">
       <intent-filter>
         <action android:name="android.intent.action.MAIN" />
         <category android:name="android.intent.category.FRAMEWORK_INSTRUMENTATION_TEST" />
       </intent-filter>
     </activity>
     <provider android:name="org.chromium.android_webview.test.TestContentProvider"
         android:authorities="org.chromium.android_webview.test.TestContentProvider" />
   </application>
 </manifest>