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