VkFunctorDrawable implementation

Bug: 115613038
Test: Turning on vulkan with appropriate webview apk does not crash and
sort of works.
Change-Id: If1504da7a35e4bd74a994ab2c2a351e6bc415a18
diff --git a/libs/hwui/renderthread/RenderThread.h b/libs/hwui/renderthread/RenderThread.h
index 5272227..1ef83fb 100644
--- a/libs/hwui/renderthread/RenderThread.h
+++ b/libs/hwui/renderthread/RenderThread.h
@@ -47,6 +47,10 @@
 class RenderState;
 class TestUtils;
 
+namespace skiapipeline {
+class VkFunctorDrawHandler;
+}
+
 namespace renderthread {
 
 class CanvasContext;
@@ -124,6 +128,7 @@
     friend class DummyVsyncSource;
     friend class android::uirenderer::TestUtils;
     friend class android::uirenderer::WebViewFunctor;
+    friend class android::uirenderer::skiapipeline::VkFunctorDrawHandler;
 
     RenderThread();
     virtual ~RenderThread();