Add unit test for vertex attribute count.

src/gpu/GrGpu.cpp

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGpu.h"
 
@@ skipping 479 matching lines @@
     return specs;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 bool GrGpu::draw(const GrPipeline& pipeline,
                  const GrPrimitiveProcessor& primProc,
                  const GrMesh* meshes,
                  int meshCount) {
     if (primProc.numAttribs() > this->caps()->maxVertexAttributes()) {
+        fStats.incNumFailedDraws();
         return false;
     }
     this->handleDirtyContext();
 
     this->onDraw(pipeline, primProc, meshes, meshCount);
     return true;
 }