Rename ShaderType enum to ShaderVisibility

Renames ShaderType in GrGLShaderBuilder to ShaderVisibility. It is now
used solely as a bitfield. Methods that previously accepted a single
ShaderType value are split into separate calls:

 - getShader -> vsGetShader, gsGetShader, fsGetShader
 - emiitFunction -> fsEmitFunction
 - appendTextureLookup -> fsAppendTextureLookup

No change in functionality. This is a refactoring to allow us to
separate the vertex/geometry and fragment parts of GrGLShaderBuilder.

R=bsalomon@google.com

Author: cdalton@nvidia.com

Review URL: https://chromiumcodereview.appspot.com/23826002

git-svn-id: http://skia.googlecode.com/svn/trunk@11044 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/effects/SkTableColorFilter.cpp b/src/effects/SkTableColorFilter.cpp
index cbcc6bc..bb72b82 100644
--- a/src/effects/SkTableColorFilter.cpp
+++ b/src/effects/SkTableColorFilter.cpp
@@ -312,19 +312,19 @@
     }
 
     builder->fsCodeAppendf("\t\t%s.a = ", outputColor);
-    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType, samplers[0], "vec2(coord.a, 0.125)");
+    builder->fsAppendTextureLookup(samplers[0], "vec2(coord.a, 0.125)");
     builder->fsCodeAppend(";\n");
 
     builder->fsCodeAppendf("\t\t%s.r = ", outputColor);
-    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType, samplers[0], "vec2(coord.r, 0.375)");
+    builder->fsAppendTextureLookup(samplers[0], "vec2(coord.r, 0.375)");
     builder->fsCodeAppend(";\n");
 
     builder->fsCodeAppendf("\t\t%s.g = ", outputColor);
-    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType, samplers[0], "vec2(coord.g, 0.625)");
+    builder->fsAppendTextureLookup(samplers[0], "vec2(coord.g, 0.625)");
     builder->fsCodeAppend(";\n");
 
     builder->fsCodeAppendf("\t\t%s.b = ", outputColor);
-    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType, samplers[0], "vec2(coord.b, 0.875)");
+    builder->fsAppendTextureLookup(samplers[0], "vec2(coord.b, 0.875)");
     builder->fsCodeAppend(";\n");
 
     builder->fsCodeAppendf("\t\t%s.rgb *= %s.a;\n", outputColor, outputColor);