Add GrVkInterface constructor with sepereate instance/device proc getters.

Change-Id: I8498c711ee1fa1cded71e4a7a63317a4b125272b
Reviewed-on: https://skia-review.googlesource.com/14277
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

include/gpu/vk/GrVkInterface.h

@@ -52,6 +52,12 @@ public:
                   VkDevice device,
                   uint32_t extensionFlags);
 
+    GrVkInterface(const GetInstanceProc&,
+                  const GetDeviceProc&,
+                  VkInstance instance,
+                  VkDevice device,
+                  uint32_t extensionFlags);
+
     // Validates that the GrVkInterface supports its advertised standard. This means the necessary
     // function pointers have been initialized for Vulkan version.
     bool validate(uint32_t extensionFlags) const;

src/gpu/vk/GrVkBackendContext.cpp

@@ -50,19 +50,15 @@ const uint32_t kGrVkMinimumVersion = VK_MAKE_VERSION(1, 0, 8);
 const GrVkBackendContext* GrVkBackendContext::Create(uint32_t* presentQueueIndexPtr,
                                                      CanPresentFn canPresent,
                                                      GrVkInterface::GetProc getProc) {
+    if (!getProc) {
 #ifdef SK_LINK_WITH_VULKAN
-    if (getProc == nullptr) {
+        return GrVkBackendContext::Create(vkGetInstanceProcAddr, vkGetDeviceProcAddr,
-        getProc = [](const char* proc_name,
+                                          presentQueueIndexPtr, canPresent);
-                     VkInstance instance, VkDevice device) {
-            if (device != VK_NULL_HANDLE) {
-                return vkGetDeviceProcAddr(device, proc_name);
-            }
-            return vkGetInstanceProcAddr(instance, proc_name);
-            };
-    }
 #else
-    SkASSERT(getProc != nullptr);
+        return nullptr;
 #endif
+    }
+    SkASSERT(getProc);
 
     VkPhysicalDevice physDev;
     VkDevice device;

src/gpu/vk/GrVkInterface.cpp

@@ -12,6 +12,26 @@
 #define ACQUIRE_PROC(name, instance, device) fFunctions.f##name = \
     reinterpret_cast<PFN_vk##name>(getProc("vk"#name, instance, device));
 
+GrVkInterface::GetProc make_unified_getter(const GrVkInterface::GetInstanceProc& iproc,
+                                           const GrVkInterface::GetDeviceProc& dproc) {
+    return [&iproc, &dproc](const char* proc_name, VkInstance instance, VkDevice device) {
+        if (device != VK_NULL_HANDLE) {
+            return dproc(device, proc_name);
+        }
+        return iproc(instance, proc_name);
+    };
+}
+
+GrVkInterface::GrVkInterface(const GetInstanceProc& getInstanceProc,
+                             const GetDeviceProc& getDeviceProc,
+                             VkInstance instance,
+                             VkDevice device,
+                             uint32_t extensionFlags)
+        : GrVkInterface(make_unified_getter(getInstanceProc, getDeviceProc),
+                        instance,
+                        device,
+                        extensionFlags) {}
+
 GrVkInterface::GrVkInterface(GetProc getProc,
                              VkInstance instance,
                              VkDevice device,