Use Windowing system-specific WindowContext factories.

include/gpu/vk/GrVkBackendContext.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrVkBackendContext_DEFINED
 #define GrVkBackendContext_DEFINED
 
@@ skipping 33 matching lines @@
     VkInstance                        fInstance;
     VkPhysicalDevice                  fPhysicalDevice;
     VkDevice                          fDevice;
     VkQueue                           fQueue;
     uint32_t                          fGraphicsQueueIndex;
     uint32_t                          fMinAPIVersion;
     uint32_t                          fExtensions;
     uint32_t                          fFeatures;
     SkAutoTUnref<const GrVkInterface> fInterface;
 
+    using CanPresentFn = std::function<bool(VkInstance, VkPhysicalDevice,
+                                            uint32_t queueFamilyIndex)>;
+
     // Helper function to create the default Vulkan objects needed by the GrVkGpu object
     // If presentQueueIndex is non-NULL, will try to set up presentQueue as part of device
-    // creation. canPresent() is a device-dependent function.
+    // creation using the platform-specific canPresent() function.
     static const GrVkBackendContext* Create(uint32_t* presentQueueIndex = nullptr,
-                    bool(*canPresent)(VkInstance, VkPhysicalDevice, uint32_t queueIndex,
-                                      void* platformData) = nullptr,
-                    void* platformData = nullptr);
+                                            CanPresentFn = CanPresentFn());
 
     ~GrVkBackendContext() override;
 };
 
 #endif