Temporary patch for Mac TSAN bot (with threaded Ganesh mask generation)

Change-Id: Id84e1534b00583eb2d76699386f42277d2007602
Reviewed-on: https://skia-review.googlesource.com/49900
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrSoftwarePathRenderer.cpp b/src/gpu/GrSoftwarePathRenderer.cpp
index 421dd6b..c9377e2 100644
--- a/src/gpu/GrSoftwarePathRenderer.cpp
+++ b/src/gpu/GrSoftwarePathRenderer.cpp
@@ -305,6 +305,12 @@
                 return false;
             }
 
+            // TODO: I believe the assignUniqueKeyToProxy below used to instantiate the proxy before
+            // before the draw that used the result was being flushed, so the upload was succeeding.
+            // With assignUniqueKeyToProxy no longer forcing an instantiation it will have to happen
+            // explicitly elsewhere.
+            proxy->instantiate(fResourceProvider);
+
             auto uploader = skstd::make_unique<GrMaskUploaderPrepareCallback<SoftwarePathData>>(
                     proxy, *boundsForMask, *args.fViewMatrix, *args.fShape, aa);
             GrMaskUploaderPrepareCallback<SoftwarePathData>* uploaderRaw = uploader.get();