Add WSI functions to GrVkInterface

include/gpu/vk/GrVkBackendContext.h

Index: include/gpu/vk/GrVkBackendContext.h
diff --git a/include/gpu/vk/GrVkBackendContext.h b/include/gpu/vk/GrVkBackendContext.h
index 8f4ba04584ed92e2dd2d9bfd525a91bc96d85b08..82a9f94bccd46f34cb44ebc4105a4ef05247e0a1 100644
--- a/include/gpu/vk/GrVkBackendContext.h
+++ b/include/gpu/vk/GrVkBackendContext.h
@@ -10,7 +10,7 @@
 
 #include "SkRefCnt.h"
 
-#include "vulkan/vulkan.h"
+#include "vk/GrVkDefines.h"
 
 #ifdef SK_DEBUG
 #define ENABLE_VK_LAYERS
@@ -19,8 +19,13 @@
 struct GrVkInterface;
 
 enum GrVkExtensionFlags {
-    kEXT_debug_report_GrVkExtensionFlag = 0x0001,
-    kNV_glsl_shader_GrVkExtensionFlag   = 0x0002,
+    kEXT_debug_report_GrVkExtensionFlag    = 0x0001,

[bsalomon, 2016/03/28 13:05:47]

Does this mix interface and device extensions? Do we care about separating them?
Same for features.

[jvanverth1, 2016/03/28 13:35:38]

The extensions are specified in docs just like OpenGL, with unique names. It's
just that you may need to enable them either on the interface or the device, or
both. So for this I don't think we care. Features are only a property of the
physical device.

+    kNV_glsl_shader_GrVkExtensionFlag      = 0x0002,
+    kKHR_surface_GrVkExtensionFlag         = 0x0004,
+    kKHR_swapchain_GrVkExtensionFlag       = 0x0008,
+    kKHR_win32_surface_GrVkExtensionFlag   = 0x0010,
+    kKHR_android_surface_GrVkExtensionFlag = 0x0020,
+    kKHR_xlib_surface_GrVkExtensionFlag    = 0x0040,
 };
 
 enum GrVkFeatureFlags {