Introduction of set of functions to manage generation of texture fetch shader code.  

A new set of routines have been added to GrGLShaderBuilder to emit texture fetches, taking into consideration the format of the texture to be accessed, and the channel swizzle.  
Review URL: https://codereview.appspot.com/6446072

git-svn-id: http://skia.googlecode.com/svn/trunk@4919 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLProgram.h b/src/gpu/gl/GrGLProgram.h
index 18d97d5..62c70e5 100644
--- a/src/gpu/gl/GrGLProgram.h
+++ b/src/gpu/gl/GrGLProgram.h
@@ -164,7 +164,7 @@
 
             /** Non-zero if user-supplied code will write the stage's
                 contribution to the fragment shader. */
-            uint16_t fCustomStageKey;
+            GrProgramStageFactory::StageKey fCustomStageKey;
 
             GR_STATIC_ASSERT((InConfigFlags)(uint8_t)kInConfigBitMask ==
                              kInConfigBitMask);