Create GLSLUniformHandler class for gpu backend

src/gpu/glsl/GrGLSLVertexShaderBuilder.h

Index: src/gpu/glsl/GrGLSLVertexShaderBuilder.h
diff --git a/src/gpu/glsl/GrGLSLVertexShaderBuilder.h b/src/gpu/glsl/GrGLSLVertexShaderBuilder.h
index b76721fd00b82cf3e4f5b0e0ddbb707f13693129..7c624cee654e8c4d956174f398c3989ad956bfb4 100644
--- a/src/gpu/glsl/GrGLSLVertexShaderBuilder.h
+++ b/src/gpu/glsl/GrGLSLVertexShaderBuilder.h
@@ -13,6 +13,9 @@
 
 class GrGLSLVarying;
 
+// Enough precision to represent 1 / 2048 accurately in printf
+#define GR_SIGNIFICANT_POW2_DECIMAL_DIG 11
+
 class GrGLSLVertexBuilder : public GrGLSLShaderBuilder {
 public:
     GrGLSLVertexBuilder(GrGLSLProgramBuilder* program);