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/SkGpuDevice_drawTexture.cpp b/src/gpu/SkGpuDevice_drawTexture.cpp
index fc32c27..23a4467 100644
--- a/src/gpu/SkGpuDevice_drawTexture.cpp
+++ b/src/gpu/SkGpuDevice_drawTexture.cpp
@@ -241,7 +241,7 @@
     if (attemptDrawTexture && can_use_draw_texture(paint)) {
         // We've done enough checks above to allow us to pass ClampNearest() and not check for
         // scaling adjustments.
-        auto proxy = producer->refTextureProxyForParams(GrSamplerState::ClampNearest(), nullptr);
+        auto proxy = producer->refTextureProxyForParams(GrSamplerState::Filter::kNearest, nullptr);
         if (!proxy) {
             return;
         }
@@ -529,7 +529,7 @@
             uint32_t uniqueID;
             proxy = image->refPinnedTextureProxy(this->context(), &uniqueID);
             if (!proxy) {
-                proxy = image->asTextureProxyRef(this->context(), GrSamplerState::ClampBilerp(),
+                proxy = image->asTextureProxyRef(this->context(), GrSamplerState::Filter::kBilerp,
                                                  nullptr);
             }
         }