remove one place we read from gpu key in effects

BUG=skia:

Review URL: https://codereview.chromium.org/761643002
diff --git a/src/effects/gradients/SkRadialGradient.cpp b/src/effects/gradients/SkRadialGradient.cpp
index 2066eb6..a891e5f 100644
--- a/src/effects/gradients/SkRadialGradient.cpp
+++ b/src/effects/gradients/SkRadialGradient.cpp
@@ -560,18 +560,18 @@
 /////////////////////////////////////////////////////////////////////
 
 void GrGLRadialGradient::emitCode(GrGLFPBuilder* builder,
-                                  const GrFragmentProcessor&,
+                                  const GrFragmentProcessor& fp,
                                   const GrProcessorKey& key,
                                   const char* outputColor,
                                   const char* inputColor,
                                   const TransformedCoordsArray& coords,
                                   const TextureSamplerArray& samplers) {
-    uint32_t baseKey = key.get32(0);
-    this->emitUniforms(builder, baseKey);
+    const GrGradientEffect& ge = fp.cast<GrGradientEffect>();
+    this->emitUniforms(builder, ge);
     SkString t("length(");
     t.append(builder->getFragmentShaderBuilder()->ensureFSCoords2D(coords, 0));
     t.append(")");
-    this->emitColor(builder, t.c_str(), baseKey, outputColor, inputColor, samplers);
+    this->emitColor(builder, ge, t.c_str(), outputColor, inputColor, samplers);
 }
 
 /////////////////////////////////////////////////////////////////////