Make onPrepareDraws const

src/gpu/batches/GrDrawVerticesBatch.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrDrawVerticesBatch.h"
 
 #include "GrBatchFlushState.h"
@@ skipping 74 matching lines @@
         fGeoData[0].fColor = overrideColor;
         fGeoData[0].fColors.reset();
         fVariableColor = false;
     }
     fCoverageIgnored = !overrides.readsCoverage();
     if (!overrides.readsLocalCoords()) {
         fGeoData[0].fLocalCoords.reset();
     }
 }
 
-void GrDrawVerticesBatch::onPrepareDraws(Target* target) {
+void GrDrawVerticesBatch::onPrepareDraws(Target* target) const {
     bool hasLocalCoords = !fGeoData[0].fLocalCoords.isEmpty();
     int colorOffset = -1, texOffset = -1;
     SkAutoTUnref<const GrGeometryProcessor> gp(
         set_vertex_attributes(hasLocalCoords, &colorOffset, &texOffset, fViewMatrix,
                               fCoverageIgnored));
     target->initDraw(gp, this->pipeline());
 
     size_t vertexStride = gp->getVertexStride();
 
     SkASSERT(vertexStride == sizeof(SkPoint) + (hasLocalCoords ? sizeof(SkPoint) : 0)
@@ skipping 212 matching lines @@
     geometry.fColor = GrRandomColor(random);
     return GrDrawVerticesBatch::Create(geometry, type, viewMatrix,
                                        positions.begin(), vertexCount,
                                        indices.begin(), hasIndices ? vertexCount : 0,
                                        colors.begin(),
                                        texCoords.begin(),
                                        bounds);
 }
 
 #endif