Revert of Make a single GrSingleOwner in GrContext

src/gpu/GrDrawingManager.h

Index: src/gpu/GrDrawingManager.h
diff --git a/src/gpu/GrDrawingManager.h b/src/gpu/GrDrawingManager.h
index df6c71a322eb06069815446f794bedac5e90f32a..c72dad976bd184b7b88c48a143d8c40ef5c96507 100644
--- a/src/gpu/GrDrawingManager.h
+++ b/src/gpu/GrDrawingManager.h
@@ -16,7 +16,6 @@
 
 class GrContext;
 class GrDrawContext;
-class GrSingleOWner;
 class GrSoftwarePathRenderer;
 class GrTextContext;
 
@@ -54,11 +53,9 @@
     static bool ProgramUnitTest(GrContext* context, int maxStages);
 
 private:
-    GrDrawingManager(GrContext* context, const GrDrawTarget::Options& optionsForDrawTargets,
-                     GrSingleOwner* singleOwner)
+    GrDrawingManager(GrContext* context, const GrDrawTarget::Options& optionsForDrawTargets)
         : fContext(context)
         , fOptionsForDrawTargets(optionsForDrawTargets)
-        , fSingleOwner(singleOwner)
         , fAbandoned(false)
         , fNVPRTextContext(nullptr)
         , fPathRendererChain(nullptr)
@@ -81,9 +78,6 @@
     GrContext*                  fContext;
     GrDrawTarget::Options       fOptionsForDrawTargets;
 
-    // In debug builds we guard against improper thread handling
-    GrSingleOwner*              fSingleOwner;
-
     bool                        fAbandoned;
     SkTDArray<GrDrawTarget*>    fDrawTargets;