Some more improvements/fixes to the VulkanViewer

tools/vulkan/Window.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "Window.h"
 
 #include "SkSurface.h"
@@ skipping 43 matching lines @@
     SkSurface* backbuffer = fTestContext->getBackbufferSurface();
     if (backbuffer) {
         // draw into the canvas of this surface
         SkCanvas* canvas = backbuffer->getCanvas();
 
         fPaintFunc(canvas, fPaintUserData);
 
         canvas->flush();
 
         fTestContext->swapBuffers();
+    } else {
+        // try recreating testcontext
     }
 
 }
 
 
 void Window::onResize(uint32_t w, uint32_t h) {
     fTestContext->resize(w, h);
 }