Update Android build to API level 17 and SDK Tools version 21

testing/android/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"
       package="org.chromium.native_test"
       android:versionCode="1"
       android:versionName="1.0">
 
-    <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="14" />
+    <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="17" />
 
     <application android:label="ChromeNativeTests">
         <activity android:name=".ChromeNativeTestActivity"
                 android:label="ChromeNativeTest"
                 android:configChanges="orientation|keyboardHidden">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
     </application>
 
     <!-- TODO(jrg): add more permissions as needed by unit tests. -->
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.WAKE_LOCK"/>
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 
 </manifest>