added support for PLS path rendering

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index d1b0802721e97e8005f3491238da1c295eeb429e..0122b81c626190b293e77709680802c69a051d15 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -35,6 +35,8 @@ class GrTransferBuffer;
 class GrVertexBuffer;
 class GrVertices;
 
+//#define ENABLE_PLS
+
 class GrGpu : public SkRefCnt {
 public:
     /**
@@ -331,6 +333,9 @@ public:
 
     void draw(const DrawArgs&, const GrVertices&);
 
+    // Called by drawtarget when flushing. Provides a hook for working around an ARM PLS driver bug.
+    virtual void performFlushWorkaround();
+
     ///////////////////////////////////////////////////////////////////////////
     // Debugging and Stats