Move the DMSAA surface flag into the public API

Bug: skia:11396
Change-Id: Iad175ea9727e0b18b94a7af341c831e03da46880
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/427484
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index af44d71..061c4f7 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -379,7 +379,7 @@
     displayParams.fGrContextOptions.fSuppressPrints = true;
     if (FLAGS_dmsaa) {
         displayParams.fSurfaceProps = SkSurfaceProps(
-                displayParams.fSurfaceProps.flags() | kDMSAA_SkSurfacePropsPrivateFlag,
+                displayParams.fSurfaceProps.flags() | SkSurfaceProps::kDynamicMSAA_Flag,
                 displayParams.fSurfaceProps.pixelGeometry());
     }
     fWindow->setRequestedDisplayParams(displayParams);