Rename GrDrawingMgr::abandon to wasAbandoned & add a matching entry point to GrDrawingContext

include/gpu/GrDrawContext.h

Index: include/gpu/GrDrawContext.h
diff --git a/include/gpu/GrDrawContext.h b/include/gpu/GrDrawContext.h
index 1ffa987f8a39569e03392101320c562049111a24..7409da334b6fa6749400cc15c3bc85be465daf24 100644
--- a/include/gpu/GrDrawContext.h
+++ b/include/gpu/GrDrawContext.h
@@ -264,6 +264,8 @@ public:
     int numColorSamples() const { return fRenderTarget->numColorSamples(); }
     bool isGammaCorrect() const { return fSurfaceProps.isGammaCorrect(); }
 
+    bool wasAbandoned() const;
+
     GrRenderTarget* accessRenderTarget() { return fRenderTarget.get(); }
 
     sk_sp<GrRenderTarget> renderTarget() { return fRenderTarget; }