cc: Remove auto use with smart pointers.

cc/test/test_context_provider.cc

Index: cc/test/test_context_provider.cc
diff --git a/cc/test/test_context_provider.cc b/cc/test/test_context_provider.cc
index 2a2b6f6e67e766056e95c2bc094154069b538b2f..4c24fe1efebaaa4bcdc376212aa606f4345270fb 100644
--- a/cc/test/test_context_provider.cc
+++ b/cc/test/test_context_provider.cc
@@ -95,7 +95,8 @@ class GrContext* TestContextProvider::GrContext() {
   if (gr_context_)
     return gr_context_.get();
 
-  auto null_interface = skia::AdoptRef(GrGLCreateNullInterface());
+  skia::RefPtr<const GrGLInterface> null_interface =
+      skia::AdoptRef(GrGLCreateNullInterface());
   gr_context_ = skia::AdoptRef(GrContext::Create(
       kOpenGL_GrBackend,
       reinterpret_cast<GrBackendContext>(null_interface.get())));