Add appendPrecisionModifier method to GrGLSLShaderBuilder

src/gpu/glsl/GrGLSLShaderVar.h

Index: src/gpu/glsl/GrGLSLShaderVar.h
diff --git a/src/gpu/glsl/GrGLSLShaderVar.h b/src/gpu/glsl/GrGLSLShaderVar.h
index a7d7479d3908c5d3dfdb2703972af12366a389da..9d162ecaa4b5f05f6808bbf9a7be342f32ff0fd1 100644
--- a/src/gpu/glsl/GrGLSLShaderVar.h
+++ b/src/gpu/glsl/GrGLSLShaderVar.h
@@ -174,8 +174,9 @@ public:
             out->append(" ");
         }
         GrSLType effectiveType = this->getType();
-        if (GrSLTypeAcceptsPrecision(effectiveType)) {
-            out->append(PrecisionString(glslCaps, fPrecision));
+        if (glslCaps->usesPrecisionModifiers() && GrSLTypeAcceptsPrecision(effectiveType)) {
+            // Desktop GLSL has added precision qualifiers but they don't do anything.
+            out->appendf("%s ", GrGLSLPrecisionString(fPrecision));
         }
         if (this->isArray()) {
             if (this->isUnsizedArray()) {
@@ -210,23 +211,6 @@ public:
                      fUseUniformFloatArrays ? "" : ".x");
     }
 
-    static const char* PrecisionString(const GrGLSLCaps* glslCaps, GrSLPrecision p) {
-        // Desktop GLSL has added precision qualifiers but they don't do anything.
-        if (glslCaps->usesPrecisionModifiers()) {
-            switch (p) {
-                case kLow_GrSLPrecision:
-                    return "lowp ";
-                case kMedium_GrSLPrecision:
-                    return "mediump ";
-                case kHigh_GrSLPrecision:
-                    return "highp ";
-                default:
-                    SkFAIL("Unexpected precision type.");
-            }
-        }
-        return "";
-    }
-
 private:
     static const char* TypeModifierString(const GrGLSLCaps* glslCaps, TypeModifier t) {
         GrGLSLGeneration gen = glslCaps->generation();