Set up to use new GrDirectContext factories in Chrome

Here is the Chrome-side CL waiting on this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/2297920 Use new GrDirectContext factories instead of deprecated GrContext ones)

Change-Id: Ic607c8f4d3b87b38b5a56a2c44012b7402e074dd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/302583
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/include/gpu/GrDirectContext.h b/include/gpu/GrDirectContext.h
index 8270dd5..8a0b237 100644
--- a/include/gpu/GrDirectContext.h
+++ b/include/gpu/GrDirectContext.h
@@ -12,7 +12,7 @@
 
 class GrAtlasManager;
 
-class GrDirectContext : public GrContext {
+class SK_API GrDirectContext : public GrContext {
 public:
 #ifdef SK_GL
     /**