Create GLSLUniformHandler class for gpu backend

BUG=skia:

Review URL: https://codereview.chromium.org/1490283004
diff --git a/src/effects/gradients/SkRadialGradient.cpp b/src/effects/gradients/SkRadialGradient.cpp
index 7be8ed1..52d0639 100644
--- a/src/effects/gradients/SkRadialGradient.cpp
+++ b/src/effects/gradients/SkRadialGradient.cpp
@@ -415,7 +415,8 @@
 #if SK_SUPPORT_GPU
 
 #include "SkGr.h"
-#include "gl/builders/GrGLProgramBuilder.h"
+#include "glsl/GrGLSLCaps.h"
+#include "glsl/GrGLSLFragmentShaderBuilder.h"
 
 class GrGLRadialGradient : public GrGLGradientEffect {
 public:
@@ -499,12 +500,12 @@
 
 void GrGLRadialGradient::emitCode(EmitArgs& args) {
     const GrRadialGradient& ge = args.fFp.cast<GrRadialGradient>();
-    this->emitUniforms(args.fBuilder, ge);
+    this->emitUniforms(args.fUniformHandler, ge);
     SkString t("length(");
     t.append(args.fFragBuilder->ensureFSCoords2D(args.fCoords, 0));
     t.append(")");
-    this->emitColor(args.fBuilder,
-                    args.fFragBuilder,
+    this->emitColor(args.fFragBuilder,
+                    args.fUniformHandler,
                     args.fGLSLCaps,
                     ge, t.c_str(),
                     args.fOutputColor,