ES31: Add DispatchComputeIndirect suport for OpenGL backend

BUG=angleproject:2270
TEST=dEQP-GLES31.functional.compute.indirect_dispatch.*

Change-Id: Id062a80188b2a37f28833aaae8e6d31bac382276
Reviewed-on: https://chromium-review.googlesource.com/802763
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/vulkan/ContextVk.cpp b/src/libANGLE/renderer/vulkan/ContextVk.cpp
index 1cbb14d..cae6e09 100644
--- a/src/libANGLE/renderer/vulkan/ContextVk.cpp
+++ b/src/libANGLE/renderer/vulkan/ContextVk.cpp
@@ -884,6 +884,12 @@
     return gl::InternalError();
 }
 
+gl::Error ContextVk::dispatchComputeIndirect(const gl::Context *context, GLintptr indirect)
+{
+    UNIMPLEMENTED();
+    return gl::InternalError();
+}
+
 gl::Error ContextVk::memoryBarrier(const gl::Context *context, GLbitfield barriers)
 {
     UNIMPLEMENTED();