Enable SkiaPipelines to interoperate with existing GlesDriver configs.

Test: hwui unit tests
Change-Id: Icd94d0e21130d86fb5514801f999d0018a69e151
diff --git a/libs/hwui/debug/NullGlesDriver.cpp b/libs/hwui/debug/NullGlesDriver.cpp
index e9dbc74..8fbe4bf 100644
--- a/libs/hwui/debug/NullGlesDriver.cpp
+++ b/libs/hwui/debug/NullGlesDriver.cpp
@@ -20,6 +20,11 @@
 namespace uirenderer {
 namespace debug {
 
+sk_sp<const GrGLInterface> NullGlesDriver::getSkiaInterface() {
+    sk_sp<const GrGLInterface> skiaInterface(GrGLCreateNullInterface());
+    return skiaInterface;
+}
+
 struct {
     GLboolean scissorEnabled;
 } gState;