Don't issue texture barriers for RT's with separate storage

src/gpu/GrTargetCommands.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTargetCommands_DEFINED
 #define GrTargetCommands_DEFINED
 
@@ skipping 224 matching lines @@
         void execute(GrGpu*) override;
 
         SkAutoTUnref<State>    fState;
         SkAutoTUnref<GrBatch>  fBatch;
 
     private:
         GrBatchTarget*         fBatchTarget;
     };
 
     struct XferBarrier : public Cmd {
-        XferBarrier() : Cmd(kXferBarrier_CmdType) {}
+        XferBarrier(GrRenderTarget* rt)
+            : Cmd(kXferBarrier_CmdType)
+            , fRenderTarget(rt) {
+        }
 
         void execute(GrGpu*) override;
 
         GrXferBarrierType   fBarrierType;
+
+    private:
+        GrPendingIOResource<GrRenderTarget, kWrite_GrIOType> fRenderTarget;
     };
 
     static const int kCmdBufferInitialSizeInBytes = 8 * 1024;
 
     typedef void* TCmdAlign; // This wouldn't be enough align if a command used long double.
     typedef GrTRecorder<Cmd, TCmdAlign> CmdBuffer;
 
     CmdBuffer* cmdBuffer() { return &fCmdBuffer; }
     GrBatchTarget* batchTarget() { return &fBatchTarget; }
 
     CmdBuffer                           fCmdBuffer;
     GrBatchTarget                       fBatchTarget;
 };
 
 #endif