Use texture barriers to read directly from the RT

src/gpu/GrInOrderDrawBuffer.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrInOrderDrawBuffer_DEFINED
 #define GrInOrderDrawBuffer_DEFINED
 
@@ skipping 113 matching lines @@
                      const GrStencilSettings&,
                      const PipelineInfo&) override;
     void onClear(const SkIRect* rect,
                  GrColor color,
                  bool canIgnoreRect,
                  GrRenderTarget* renderTarget) override;
     bool onCopySurface(GrSurface* dst,
                        GrSurface* src,
                        const SkIRect& srcRect,
                        const SkIPoint& dstPoint) override;
+    void onBlendBarrier() override;
 
     // Attempts to concat instances from info onto the previous draw. info must represent an
     // instanced draw. The caller must have already recorded a new draw state and clip if necessary.
     int concatInstancedDraw(const DrawInfo&);
 
     // We lazily record clip changes in order to skip clips that have no effect.
     void recordClipIfNecessary();
     // Records any trace markers for a command
     void recordTraceMarkersIfNecessary(GrTargetCommands::Cmd*);
     SkString getCmdString(int index) const {
@@ skipping 11 matching lines @@
     GrTargetCommands                    fCommands;
     SkTArray<GrTraceMarkerSet, false>   fGpuCmdMarkers;
     SkChunkAlloc                        fPathIndexBuffer;
     SkChunkAlloc                        fPathTransformBuffer;
     uint32_t                            fDrawID;
 
     typedef GrFlushToGpuDrawTarget INHERITED;
 };
 
 #endif