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/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index f6b70fc..24aef28 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -130,16 +130,16 @@
     SkString coords;
     fEffectMatrix.emitCodeMakeFSCoords2D(builder, key, &coords);
     fOffsetVar = builder->addUniform(
-        GrGLShaderBuilder::kFragment_ShaderType |
-        GrGLShaderBuilder::kVertex_ShaderType,
+        GrGLShaderBuilder::kFragment_Visibility |
+        GrGLShaderBuilder::kVertex_Visibility,
         kVec2f_GrSLType, "uOffset");
     fZoomVar = builder->addUniform(
-        GrGLShaderBuilder::kFragment_ShaderType |
-        GrGLShaderBuilder::kVertex_ShaderType,
+        GrGLShaderBuilder::kFragment_Visibility |
+        GrGLShaderBuilder::kVertex_Visibility,
         kVec2f_GrSLType, "uZoom");
     fInsetVar = builder->addUniform(
-        GrGLShaderBuilder::kFragment_ShaderType |
-        GrGLShaderBuilder::kVertex_ShaderType,
+        GrGLShaderBuilder::kFragment_Visibility |
+        GrGLShaderBuilder::kVertex_Visibility,
         kVec2f_GrSLType, "uInset");
 
     builder->fsCodeAppendf("\t\tvec2 coord = %s;\n", coords.c_str());
@@ -165,7 +165,7 @@
 
     builder->fsCodeAppend("\t\tvec2 mix_coord = mix(coord, zoom_coord, weight);\n");
     builder->fsCodeAppend("\t\tvec4 output_color = ");
-    builder->appendTextureLookup(GrGLShaderBuilder::kFragment_ShaderType, samplers[0], "mix_coord");
+    builder->fsAppendTextureLookup(samplers[0], "mix_coord");
     builder->fsCodeAppend(";\n");
 
     builder->fsCodeAppendf("\t\t%s = output_color;", outputColor);