Expand GrTextureProxy to handle highestFilterMode


Once TextureProxies aren't instantiated in the TextureSamplers, the they will need to be able to supply this information.

split out of: https://skia-review.googlesource.com/c/10484/ (Omnibus: Push instantiation of GrTextures later (post TextureSampler))
Change-Id: I66555c0746131f565862f7a30d54ff1d458d2062
Reviewed-on: https://skia-review.googlesource.com/15819
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/include/private/GrTextureProxy.h b/include/private/GrTextureProxy.h
index ee954dc..61e8020 100644
--- a/include/private/GrTextureProxy.h
+++ b/include/private/GrTextureProxy.h
@@ -26,6 +26,8 @@
 
     void setMipColorMode(SkDestinationSurfaceColorMode colorMode);
 
+    GrSamplerParams::FilterMode highestFilterMode() const;
+
 protected:
     friend class GrSurfaceProxy; // for ctors