Add flag for window rectangles to GrRenderTarget

src/gpu/vk/GrVkRenderTarget.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 GrVkRenderTarget_DEFINED
 #define GrVkRenderTarget_DEFINED
@@ skipping 108 matching lines @@
                      const GrVkImageView* resolveAttachmentView,
                      GrVkImage::Wrapped wrapped);
 
     GrVkRenderTarget(GrVkGpu* gpu,
                      SkBudgeted,
                      const GrSurfaceDesc& desc,
                      const GrVkImageInfo& info,
                      const GrVkImageView* colorAttachmentView,
                      GrVkImage::Wrapped wrapped);
 
+    constexpr static Flags ComputeFlags(/*???*/);
+
     static GrVkRenderTarget* Create(GrVkGpu*, SkBudgeted, const GrSurfaceDesc&,
                                     const GrVkImageInfo&, GrVkImage::Wrapped wrapped);
 
     bool completeStencilAttachment() override;
 
     void releaseInternalObjects();
     void abandonInternalObjects();
 
     const GrVkFramebuffer*     fFramebuffer;
     int                        fColorValuesPerPixel;
 
     // This is a cached pointer to a simple render pass. The render target should unref it
     // once it is done with it.
     const GrVkRenderPass*      fCachedSimpleRenderPass;
     // This is a handle to be used to quickly get compatible GrVkRenderPasses for this render target
     GrVkResourceProvider::CompatibleRPHandle fCompatibleRPHandle;
 };
 
 #endif