Add flag for window rectangles to GrRenderTarget

src/gpu/GrRenderTargetPriv.h

Index: src/gpu/GrRenderTargetPriv.h
diff --git a/src/gpu/GrRenderTargetPriv.h b/src/gpu/GrRenderTargetPriv.h
index db66bc33163bfdeb69559e6bb49b8a3305577027..2c828ec59a2120211aaca1f7bbc9ac13a69fe006 100644
--- a/src/gpu/GrRenderTargetPriv.h
+++ b/src/gpu/GrRenderTargetPriv.h
@@ -35,7 +35,10 @@ public:
     const GrGpu::MultisampleSpecs& getMultisampleSpecs(const GrStencilSettings& stencil) const;
     uint8_t& accessMultisampleSpecsID() { return fRenderTarget->fMultisampleSpecsID; }
 
-    GrRenderTarget::SampleConfig sampleConfig() const { return fRenderTarget->fSampleConfig; }
+    typedef GrRenderTarget::Flags Flags;
+
+    Flags flags() const { return fRenderTarget->fFlags; }
+    bool supportsWindowRectangles() const { return this->flags() & Flags::kWindowRectsSupport; }
 
 private:
     explicit GrRenderTargetPriv(GrRenderTarget* renderTarget) : fRenderTarget(renderTarget) {}