Extract a GrRenderTask base class from GrOpList

This is a more abstract representation of something that can
participate in the DAG by modifying a GrSurfaceProxy's pixels. This
will serve as the direct base class for future DAG participants that
aren't opLists, and help to eventually remove GrTextureOpList.

Bug: skia:
Change-Id: Ia903c0188e0f6a6602781b90ee8da87ba3cc13f8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/231277
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
diff --git a/src/gpu/GrRenderTargetOpList.h b/src/gpu/GrRenderTargetOpList.h
index 6106c76..369d9cd 100644
--- a/src/gpu/GrRenderTargetOpList.h
+++ b/src/gpu/GrRenderTargetOpList.h
@@ -227,7 +227,7 @@
         SkRect fBounds;
     };
 
-    void purgeOpsWithUninstantiatedProxies() override;
+    void handleInternalAllocationFailure() override;
 
     void gatherProxyIntervals(GrResourceAllocator*) const override;