Add Sleep on windows GrVkGpu dtor to avoid fence bug

src/gpu/vk/GrVkGpu.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrVkGpu.h"
 
 #include "GrContextOptions.h"
@@ skipping 136 matching lines @@
     fHeaps[kCopyWriteBuffer_Heap].reset(new GrVkHeap(this, GrVkHeap::kSubAlloc_Strategy, 16*1024*1024));
 }
 
 GrVkGpu::~GrVkGpu() {
     fCurrentCmdBuffer->end(this);
     fCurrentCmdBuffer->unref(this);
 
     // wait for all commands to finish
     fResourceProvider.checkCommandBuffers();
     SkDEBUGCODE(VkResult res = ) VK_CALL(QueueWaitIdle(fQueue));
+
+    // On windows, sometimes calls to QueueWaitIdle return before actually signalling the fences
+    // on the command buffers even though they have completed. This causes an assert to fire when
+    // destroying the command buffers. Currently this ony seems to happen on windows, so we add a
+    // sleep to make sure the fence singals.
+#ifdef SK_DEBUG
+#if defined(SK_BUILD_FOR_WIN)
+    Sleep(10); // In milliseconds
+#else
+    // Uncomment if above bug happens on non windows build.
+    // sleep(1);        // In seconds
+#endif
+#endif
+
     // VK_ERROR_DEVICE_LOST is acceptable when tearing down (see 4.2.4 in spec)
     SkASSERT(VK_SUCCESS == res || VK_ERROR_DEVICE_LOST == res);
 
     // must call this just before we destroy the VkDevice
     fResourceProvider.destroyResources();
 
     VK_CALL(DestroyCommandPool(fDevice, fCmdPool, nullptr));
 
     shaderc_compiler_release(fCompiler);
 
@@ skipping 1262 matching lines @@
                                            GrVkRenderTarget* target,
                                            const SkIRect& bounds) {
     // Currently it is fine for us to always pass in 1 for the clear count even if no attachment
     // uses it. In the current state, we also only use the LOAD_OP_CLEAR for the color attachment
     // which is always at the first attachment.
     fCurrentCmdBuffer->beginRenderPass(this, renderPass, 1, colorClear, *target, bounds, true);
     fCurrentCmdBuffer->executeCommands(this, buffer);
     fCurrentCmdBuffer->endRenderPass(this);
 }