Add a class representing texture swizzle.

src/gpu/glsl/GrGLSLCaps.h

Index: src/gpu/glsl/GrGLSLCaps.h
diff --git a/src/gpu/glsl/GrGLSLCaps.h b/src/gpu/glsl/GrGLSLCaps.h
index 21c59e7b162f880c2074e8317fd13bdaba6c7162..eba9602e5ac270cd65f68d156d5ae96d632f5e8d 100755
--- a/src/gpu/glsl/GrGLSLCaps.h
+++ b/src/gpu/glsl/GrGLSLCaps.h
@@ -11,6 +11,7 @@
 
 #include "GrCaps.h"
 #include "GrGLSL.h"
+#include "GrSwizzle.h"
 
 class GrGLSLCaps : public GrShaderCaps {
 public:
@@ -104,14 +105,14 @@ public:
         return fExternalTextureExtensionString;
     }
 
-    bool mustSwizzleInShader() const { return fMustSwizzleInShader; }
-
     /**
-     * Returns a string which represents how to map from an internal GLFormat to a given
-     * GrPixelConfig. The function mustSwizzleInShader determines whether this swizzle is applied
-     * in the generated shader code or using sample state in the 3D API.
+     * Given a texture's config, this determines what swizzle must be appended to accesses to the
+     * texture in generated shader code. Swizzling may be implemented in texture parameters or a
+     * sampler rather than in the shader. In this case the shader swizzle will always be "rgba".
      */
-    const char* getSwizzleMap(GrPixelConfig config) const { return fConfigSwizzle[config]; }
+    const GrSwizzle& configTextureSwizzle(GrPixelConfig config) const {
+        return fConfigTextureSwizzle[config];
+    }
 
     GrGLSLGeneration generation() const { return fGLSLGeneration; }
 
@@ -148,13 +149,11 @@ private:
 
     AdvBlendEqInteraction fAdvBlendEqInteraction;
 
-    bool        fMustSwizzleInShader;
-    const char* fConfigSwizzle[kGrPixelConfigCnt];
+    GrSwizzle fConfigTextureSwizzle[kGrPixelConfigCnt];
 
     friend class GrGLCaps;  // For initialization.
 
     typedef GrShaderCaps INHERITED;
 };
 
-
 #endif