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/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 329e6c7..ca6386a 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -832,7 +832,7 @@
 GrGLGradientEffect::~GrGLGradientEffect() { }
 
 void GrGLGradientEffect::emitYCoordUniform(GrGLShaderBuilder* builder) {
-    fFSYUni = builder->addUniform(GrGLShaderBuilder::kFragment_ShaderType,
+    fFSYUni = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
                                   kFloat_GrSLType, "GradientYCoordFS");
 }
 
@@ -877,10 +877,7 @@
                            gradientTValue,
                            builder->getUniformVariable(fFSYUni).c_str());
     builder->fsCodeAppendf("\t%s = ", outputColor);
-    builder->appendTextureLookupAndModulate(GrGLShaderBuilder::kFragment_ShaderType,
-                                            inputColor,
-                                            sampler,
-                                            "coord");
+    builder->fsAppendTextureLookupAndModulate(inputColor, sampler, "coord");
     builder->fsCodeAppend(";\n");
 }