title: A lot of NPE of DeviceMotionService happen recently
body: <p>Recently my app on Google Play Store get a lot of NPE of DeviceMotionService. Following is the stack:</p>
  
  <pre><code>java.lang.NullPointerException
      at android.webkit.DeviceMotionService$2.run(DeviceMotionService.java:103)
      at android.os.Handler.handleCallback(Handler.java:615)
      at android.os.Handler.dispatchMessage(Handler.java:92)
      at android.os.Looper.loop(Looper.java:137)
      at android.webkit.WebViewCore$WebCoreThread.run(WebViewCore.java:1067)
      at java.lang.Thread.run(Thread.java:856)
  </code></pre>
  
  <p>I have no clue about this issue. I did use <code>WebView</code> in my app. But I checked source code. It seems a deep function in android framework/webkit.</p>