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.h b/src/gpu/glsl/GrGLSLProgramBuilder.h
index 1b82a0c..99d6f8b 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.h
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.h
@@ -161,7 +161,7 @@
                                     SkString output,
                                     SkTArray<std::unique_ptr<GrGLSLFragmentProcessor>>*);
     void emitAndInstallXferProc(const SkString& colorIn, const SkString& coverageIn);
-    SamplerHandle emitSampler(const GrSurfaceProxy*, const GrSamplerState&, const GrSwizzle&,
+    SamplerHandle emitSampler(const GrSurfaceProxy*, GrSamplerState, const GrSwizzle&,
                               const char* name);
     bool checkSamplerCounts();