Remove unused GrFlushFlags.

This also adds back default flush() calls which simply do a flush
without any submit.

Change-Id: Ia8c92bbdecd515d871abfa6364592f502e98656b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/298818
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
diff --git a/gm/asyncrescaleandread.cpp b/gm/asyncrescaleandread.cpp
index bd55929..3ad5b8f 100644
--- a/gm/asyncrescaleandread.cpp
+++ b/gm/asyncrescaleandread.cpp
@@ -112,9 +112,7 @@
     };
 
     *cleanup = {[context, backendTextures] {
-        GrFlushInfo flushInfo;
-        flushInfo.fFlags = kSyncCpu_GrFlushFlag;
-        context->flush(flushInfo);
+        context->flush();
         context->submit(true);
         context->deleteBackendTexture(backendTextures[0]);
         context->deleteBackendTexture(backendTextures[1]);