[android_webview] Add test shell for webview.

android_webview/test_apk/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.android_webview.test">
     <!-- We add an application tag here just so that we can indicate that this
          package needs to link against the android.test library, which is
          needed when building test cases. -->
     <application>
         <uses-library android:name="android.test.runner" />
         <provider android:name="TestContentProvider"
             android:authorities="org.chromium.android_webview.test.TestContentProvider" />
     </application>
     <!-- TODO(joth): Change minSdkVersion to 16 when crbug/161864 lands. -->
     <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="17" />
     <instrumentation android:name="android.test.InstrumentationTestRunner"
         android:targetPackage="org.chromium.android_webview"
         android:label="Tests for org.chromium.android_webview"/>
     <uses-permission android:name="android.permission.RUN_INSTRUMENTATION" />
     <uses-permission android:name="android.permission.INJECT_EVENTS" />
     <uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" />
     <uses-permission android:name="android.permission.READ_LOGS"/>
     <uses-permission android:name="android.permission.WAKE_LOCK" />
 </manifest>