Infer sampler precision from pixel config

src/gpu/glsl/GrGLSLProgramBuilder.cpp

Index: src/gpu/glsl/GrGLSLProgramBuilder.cpp
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.cpp b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
index 512d9d14d9302c272b55a94df65e619f9cc1caa3..928935d45021461b394ce2e5d0ac09f654744249 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.cpp
@@ -241,10 +241,11 @@ void GrGLSLProgramBuilder::emitSamplers(const GrProcessor& processor,
                              1 << GrGLSLShaderBuilder::kExternalTexture_GLSLPrivateFeature,
                              externalFeatureString);
         }
+        GrSLPrecision precision = GrPixelConfigPrecision(access.getTexture()->config());
         name.printf("Sampler%d", t);
         localSamplerUniforms[t] = this->uniformHandler()->addUniform(access.getVisibility(),
                                                                      samplerType,
-                                                                     access.getPrecision(),
+                                                                     precision,
                                                                      name.c_str());
         outSamplers->emplace_back(localSamplerUniforms[t], access);
     }