Add flag for window rectangles to GrRenderTarget

src/gpu/gl/GrGLRenderTarget.h

Index: src/gpu/gl/GrGLRenderTarget.h
diff --git a/src/gpu/gl/GrGLRenderTarget.h b/src/gpu/gl/GrGLRenderTarget.h
index edf35a1a5c7cee1f3f1e85318d11f258a13893e3..85e377f69acd8be6fc28e061d178b094d28ae231 100644
--- a/src/gpu/gl/GrGLRenderTarget.h
+++ b/src/gpu/gl/GrGLRenderTarget.h
@@ -13,6 +13,7 @@
 #include "GrRenderTarget.h"
 #include "SkScalar.h"
 
+class GrGLCaps;
 class GrGLGpu;
 class GrGLStencilAttachment;
 
@@ -23,11 +24,11 @@ public:
     enum { kUnresolvableFBOID = 0 };
 
     struct IDDesc {
-        GrGLuint                     fRTFBOID;
-        GrBackendObjectOwnership     fRTFBOOwnership;
-        GrGLuint                     fTexFBOID;
-        GrGLuint                     fMSColorRenderbufferID;
-        GrRenderTarget::SampleConfig fSampleConfig;
+        GrGLuint                   fRTFBOID;
+        GrBackendObjectOwnership   fRTFBOOwnership;
+        GrGLuint                   fTexFBOID;
+        GrGLuint                   fMSColorRenderbufferID;
+        bool                       fIsMixedSampled;
     };
 
     static GrGLRenderTarget* CreateWrapped(GrGLGpu*,
@@ -83,6 +84,8 @@ private:
     // Constructor for instances wrapping backend objects.
     GrGLRenderTarget(GrGLGpu*, const GrSurfaceDesc&, const IDDesc&, GrGLStencilAttachment*);
 
+    static Flags ComputeFlags(const GrGLCaps&, const IDDesc&);
+
     GrGLGpu* getGLGpu() const;
     bool completeStencilAttachment() override;