Make GrDrawState and GrEffectStage use the pending io/exec ref mechanisms.

BUG=skia:2889
R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/542723004
diff --git a/src/gpu/GrDrawTarget.h b/src/gpu/GrDrawTarget.h
index 814d57f..8ffc681 100644
--- a/src/gpu/GrDrawTarget.h
+++ b/src/gpu/GrDrawTarget.h
@@ -694,6 +694,10 @@
     virtual DrawToken getCurrentDrawToken() { return DrawToken(this, 0); }
 
 protected:
+    // Extend access to GrRODrawState::convertToPEndeingExec to subclasses.
+    void convertDrawStateToPendingExec(GrRODrawState* ds) {
+        ds->convertToPendingExec();
+    }
 
     enum GeometrySrcType {
         kNone_GeometrySrcType,     //<! src has not been specified