Allow implicit conversion from GrSamplerState::Filter to GrSamplerState

constexprify GrSamplerState

pass/return GrSamplerState by value (it's 3 bytes).

Remove unused function from GrTexturePriv

Change-Id: Iffecd941500acf5653f01cc88b42ff1d45678b54
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/263346
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 7ba3d40..54b97fd 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -277,7 +277,7 @@
 }
 
 GrGLSLProgramBuilder::SamplerHandle GrGLSLProgramBuilder::emitSampler(const GrSurfaceProxy* texture,
-                                                                      const GrSamplerState& state,
+                                                                      GrSamplerState state,
                                                                       const GrSwizzle& swizzle,
                                                                       const char* name) {
     ++fNumFragmentSamplers;