title: Android WebView with layer_type_software not showing HTML5 canvas content
body: <p>Since last update of Android WebView a web page with a HTML5 canvas is not displayed correctly when hardware acceleration is disabled by setting the WebView's layer type to View.LAYER_TYPE_SOFTWARE. Is there a workaround for this problem?</p>
  
  <p>When I leave out the following line of Java code:
  webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
  Then the Content is displayed correctly.</p>
  
  <h2>Java code:</h2>
  
  <pre><code>WebView webView = findViewById(R.id.webView);
  webView.getSettings().setJavaScriptEnabled(true);
  webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
  webView.loadUrl("file:///android_asset/Gradient.html");
  </code></pre>
  
  <h2>Html file test.html:</h2>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;body&gt;
  &lt;canvas id="myCanvas" width="200" height="100" style="border:1px solid #d3d3d3;"&gt;
  Your browser does not support the HTML5 canvas tag.&lt;/canvas&gt;
  &lt;script&gt;
  var c = document.getElementById("myCanvas");
  var ctx = c.getContext("2d");
  // Create gradient
  var grd = ctx.createLinearGradient(0,0,200,0);
  grd.addColorStop(0,"red");
  grd.addColorStop(1,"white");
  // Fill with gradient
  ctx.fillStyle = grd;
  ctx.fillRect(10,10,150,80);
  &lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Expected result:
  Red linear gradient in black border
  <a href="https://heiri-web.ch/Gradient.png" rel="nofollow noreferrer">https://heiri-web.ch/Gradient.png</a> </p>
  
  <p>Actual result:
  Empty black border
  <a href="https://heiri-web.ch/Empty.png" rel="nofollow noreferrer">https://heiri-web.ch/Empty.png</a></p>