Simplify adding attributes to GrGeometryProcessor

tests/PrimitiveProcessorTest.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // This is a GPU-backend specific test. It relies on static intializers to work
 
 #include "SkTypes.h"
@@ skipping 38 matching lines @@
     void onPrepareDraws(Target* target) const override {
         class GP : public GrGeometryProcessor {
         public:
             GP(int numAttribs) {
                 this->initClassID<GP>();
                 SkASSERT(numAttribs > 1);
                 for (auto i = 0; i < numAttribs; ++i) {
                     fAttribNames.push_back().printf("attr%d", i);
                 }
                 for (auto i = 0; i < numAttribs; ++i) {
-                    Attribute attribute;
-                    attribute.fType = kVec2f_GrVertexAttribType;
-                    attribute.fName = fAttribNames[i].c_str();
-                    attribute.fOffset = 2 * sizeof(float) * i;
-                    attribute.fPrecision = kDefault_GrSLPrecision;
-                    this->addVertexAttrib(attribute);
+                    this->addVertexAttrib(fAttribNames[i].c_str(), kVec2f_GrVertexAttribType);
                 }
             };
             const char* name() const override { return "Dummy GP"; }
 
             GrGLSLPrimitiveProcessor* createGLSLInstance(const GrGLSLCaps&) const override {
                 class GLSLGP : public GrGLSLGeometryProcessor {
                 public:
                     void onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) override {
                         const GP& gp = args.fGP.cast<GP>();
                         args.fVaryingHandler->emitAttributes(gp);
@@ skipping 61 matching lines @@
     // This one should fail.
     batch.reset(new Batch(attribCnt+1));
     drawContext->drawContextPriv().testingOnly_drawBatch(grPaint, batch);
     context->flush();
 #if GR_GPU_STATS
     REPORTER_ASSERT(reporter, context->getGpu()->stats()->numDraws() == 0);
     REPORTER_ASSERT(reporter, context->getGpu()->stats()->numFailedDraws() == 1);
 #endif
 }
 #endif