Introduce enum class for texture type.

This represents the GL texture "target" but at the API-neutral level. It
will be needed here because proxy's that wrap imported texture's need to
know about sampling restrictions.

Change-Id: Ie811a6f6d04ba1b04faa6908422dca64e8e447c8
Reviewed-on: https://skia-review.googlesource.com/144304
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/glsl/GrGLSLProgramBuilder.h b/src/gpu/glsl/GrGLSLProgramBuilder.h
index b1ccec8..bdc39c00 100644
--- a/src/gpu/glsl/GrGLSLProgramBuilder.h
+++ b/src/gpu/glsl/GrGLSLProgramBuilder.h
@@ -137,7 +137,7 @@
     void emitAndInstallXferProc(const SkString& colorIn, const SkString& coverageIn);
     void emitSamplers(const GrResourceIOProcessor& processor,
                       SkTArray<SamplerHandle>* outTexSamplerHandles);
-    SamplerHandle emitSampler(GrSLType samplerType, GrPixelConfig, const char* name,
+    SamplerHandle emitSampler(GrTextureType, GrPixelConfig, const char* name,
                               GrShaderFlags visibility);
     void emitFSOutputSwizzle(bool hasSecondaryOutput);
     void updateSamplerCounts(GrShaderFlags visibility);