[base] Update GrDirectContext calls to use safer API

In http://review.skia.org/750403 and http://review.skia.org/751523,
Skia modified some GrDirectContext APIs to make them less error-prone
in response to https://crbug.com/1475906.

This updates part of Android to call those modified APIs.

Change-Id: I164fcc735b3c36bf58de2f1ed9f277e90fc09325
diff --git a/libs/hwui/renderthread/VulkanManager.cpp b/libs/hwui/renderthread/VulkanManager.cpp
index ee3b2e4..90850d3 100644
--- a/libs/hwui/renderthread/VulkanManager.cpp
+++ b/libs/hwui/renderthread/VulkanManager.cpp
@@ -515,7 +515,7 @@
                         // The following flush blocks the GPU immediately instead of waiting for
                         // other drawing ops. It seems dequeue_fence is not respected otherwise.
                         // TODO: remove the flush after finding why backendSemaphore is not working.
-                        skgpu::ganesh::FlushAndSubmit(bufferInfo->skSurface);
+                        skgpu::ganesh::FlushAndSubmit(bufferInfo->skSurface.get());
                     }
                 }
             }