Add a class representing texture swizzle.

src/gpu/glsl/GrGLSLCaps.cpp

Index: src/gpu/glsl/GrGLSLCaps.cpp
diff --git a/src/gpu/glsl/GrGLSLCaps.cpp b/src/gpu/glsl/GrGLSLCaps.cpp
index cf41f8e765e8e3bb1049711d6e6d76d50d9138a6..c82d8333dff89a786a721429a7b30cb4da34e332 100755
--- a/src/gpu/glsl/GrGLSLCaps.cpp
+++ b/src/gpu/glsl/GrGLSLCaps.cpp
@@ -31,9 +31,6 @@ GrGLSLCaps::GrGLSLCaps(const GrContextOptions& options) {
     fFBFetchColorName = nullptr;
     fFBFetchExtensionString = nullptr;
     fAdvBlendEqInteraction = kNotSupported_AdvBlendEqInteraction;
-
-    fMustSwizzleInShader = false;
-    memset(fConfigSwizzle, 0, sizeof(fConfigSwizzle));
 }
 
 SkString GrGLSLCaps::dump() const {
@@ -67,8 +64,5 @@ SkString GrGLSLCaps::dump() const {
 }
 
 void GrGLSLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {
-    if (options.fUseShaderSwizzling) {
-        fMustSwizzleInShader = true;
-    }
 }