Implement support for mixed sampled render targets

src/gpu/gl/GrGLCaps.h

Index: src/gpu/gl/GrGLCaps.h
diff --git a/src/gpu/gl/GrGLCaps.h b/src/gpu/gl/GrGLCaps.h
index a1d53e30fa3093cfc0f6dca1f7d2a26e9c0f4d8a..c0e061661f8204c5eca4ae168ed58d918edcda57 100644
--- a/src/gpu/gl/GrGLCaps.h
+++ b/src/gpu/gl/GrGLCaps.h
@@ -65,8 +65,12 @@ public:
          * GL_MAX_SAMPLES value.
          */
         kES_EXT_MsToTexture_MSFBOType,
+        /**
+         * GL_NV_framebuffer_mixed_samples.
+         */
+        kMixedSamples_MSFBOType,
 
-        kLast_MSFBOType = kES_EXT_MsToTexture_MSFBOType
+        kLast_MSFBOType = kMixedSamples_MSFBOType
     };
 
     enum InvalidateFBType {
@@ -153,7 +157,8 @@ public:
     bool usesMSAARenderBuffers() const {
         return kNone_MSFBOType != fMSFBOType &&
                kES_IMG_MsToTexture_MSFBOType != fMSFBOType &&
-               kES_EXT_MsToTexture_MSFBOType != fMSFBOType;
+               kES_EXT_MsToTexture_MSFBOType != fMSFBOType &&
+               kMixedSamples_MSFBOType != fMSFBOType;
     }
 
     /**