Add appendPrecisionModifier method to GrGLSLShaderBuilder

src/gpu/glsl/GrGLSLShaderBuilder.cpp

Index: src/gpu/glsl/GrGLSLShaderBuilder.cpp
diff --git a/src/gpu/glsl/GrGLSLShaderBuilder.cpp b/src/gpu/glsl/GrGLSLShaderBuilder.cpp
index 93b9f8a57aee00d5754e68e39287e940c398e009..795e5cb585de66e0ea6c78c60f5a4af821561020 100644
--- a/src/gpu/glsl/GrGLSLShaderBuilder.cpp
+++ b/src/gpu/glsl/GrGLSLShaderBuilder.cpp
@@ -35,6 +35,12 @@ void GrGLSLShaderBuilder::declAppend(const GrGLSLShaderVar& var) {
     this->codeAppendf("%s;", tempDecl.c_str());
 }
 
+void GrGLSLShaderBuilder::appendPrecisionModifier(GrSLPrecision precision) {
+    if (fProgramBuilder->glslCaps()->usesPrecisionModifiers()) {
+        this->codeAppendf("%s ", GrGLSLPrecisionString(precision));
+    }
+}
+
 void GrGLSLShaderBuilder::emitFunction(GrSLType returnType,
                                        const char* name,
                                        int argCnt,