Implement difference clip rects with window rectangles

src/gpu/GrPipeline.h

Index: src/gpu/GrPipeline.h
diff --git a/src/gpu/GrPipeline.h b/src/gpu/GrPipeline.h
index 1457dbc3f58120861a445237a978eb7bbcf60a78..0d07deb5e61e92b7acb961fdd3ac0dddbd95b908 100644
--- a/src/gpu/GrPipeline.h
+++ b/src/gpu/GrPipeline.h
@@ -18,6 +18,7 @@
 #include "GrProgramDesc.h"
 #include "GrStencilSettings.h"
 #include "GrTypesPriv.h"
+#include "GrWindowRectangles.h"
 #include "SkMatrix.h"
 #include "SkRefCnt.h"
 
@@ -59,6 +60,7 @@ public:
         const GrCaps*               fCaps;
         GrPipelineOptimizations     fOpts;
         const GrScissorState*       fScissor;
+        const GrWindowRectangles*   fWindows;
         bool                        fHasStencilClip;
         GrXferProcessor::DstTexture fDstTexture;
     };
@@ -152,6 +154,8 @@ public:
 
     const GrScissorState& getScissorState() const { return fScissorState; }
 
+    const GrWindowRectangles& getWindowRectangles() const { return fWindows; }
+
     bool isHWAntialiasState() const { return SkToBool(fFlags & kHWAA_Flag); }
     bool snapVerticesToPixelCenters() const { return SkToBool(fFlags & kSnapVertices_Flag); }
     bool getDisableOutputConversionToSRGB() const {
@@ -219,6 +223,7 @@ private:
     typedef GrPendingProgramElement<const GrXferProcessor> ProgramXferProcessor;
     RenderTarget                        fRenderTarget;
     GrScissorState                      fScissorState;
+    GrWindowRectangles                  fWindows;
     GrStencilSettings                   fStencilSettings;
     GrDrawFace                          fDrawFace;
     uint32_t                            fFlags;