title: WebView threads never stop (WebViewCoreThread, CookieSyncManager, http[0-3])
body: <p>I use a WebView to display some internet content on one of our app's
  Activities.<br>
  The problem is that when the user switches out of this activity,
  WebView's threads keep running!<br>
  The problematic threads are:</p>
  
  <pre><code>Thread [&lt;17&gt; WebViewCoreThread] (Running)
  Thread [&lt;25&gt; CookieSyncManager] (Running)
  Thread [&lt;19&gt; http0] (Running)
  Thread [&lt;29&gt; http1] (Running)
  Thread [&lt;31&gt; http2] (Running)
  Thread [&lt;33&gt; http3] (Running)
  </code></pre>
  
  <p>Pausing each one of these threads, and checking what it is busy doing:</p>
  
  <pre><code>Thread [&lt;17&gt; WebViewCoreThread] (Suspended)
      Object.wait(long, int) line: not available [native method]
      MessageQueue(Object).wait() line: 288
      MessageQueue.next() line: 148
      Looper.loop() line: 110
      WebViewCore$WebCoreThread.run() line: 471
      Thread.run() line: 1060
  
  Thread [&lt;25&gt; CookieSyncManager] (Suspended)
      Object.wait(long, int) line: not available [native method]
      MessageQueue(Object).wait(long) line: 326
      MessageQueue.next() line: 144
      Looper.loop() line: 110
      CookieSyncManager(WebSyncManager).run() line: 90
      Thread.run() line: 1060
  
  Thread [&lt;19&gt; http0] (Suspended)
      Object.wait(long, int) line: not available [native method]
      RequestQueue(Object).wait() line: 288
      ConnectionThread.run() line: 93
  </code></pre>
  
  <p>I wonder how can I tell the <code>Looper</code> in each of those threads to quit.</p>
  
  <p>I tried calling <code>webView.destroy()</code> in the activity's <code>onPause()</code> method,
  but it had no influence.<br>
  When I disable the call for opening a web page in the webView
  ( <code>webView.loadUrl(...)</code> ), those threads naturally are not started, and
  therefore don't stay on after leaving the activity.</p>
  
  <p>Any ideas as to how I can make <code>WebView</code>'s threads stop after leaving
  their activity?</p>