Compute bounds union while combining path range draw path batches

src/gpu/batches/GrDrawPathBatch.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 "GrDrawPathBatch.h"
 
 static void pre_translate_transform_values(const float* xforms,
@@ skipping 84 matching lines @@
     }
     SkASSERT(!that->overrides().willColorBlendWithDst());
     fTotalPathCount += that->fTotalPathCount;
     while (Draw* head = that->fDraws.head()) {
         Draw* draw = fDraws.addToTail();
         draw->fInstanceData.reset(head->fInstanceData.release());
         draw->fX = head->fX;
         draw->fY = head->fY;
         that->fDraws.popHead();
     }
+    this->joinBounds(that->fBounds);
     return true;
 }
 
 void GrDrawPathRangeBatch::onDraw(GrBatchFlushState* state) {
     const Draw& head = *fDraws.head();
 
     SkMatrix drawMatrix(this->viewMatrix());
     drawMatrix.preScale(fScale, fScale);
     drawMatrix.preTranslate(head.fX, head.fY);
 
@@ skipping 86 matching lines @@
                 dst[i + 3] = xforms[i + 3];
                 dst[i + 4] = xforms[i + 4];
                 dst[i + 5] = xforms[i + 3] * x + xforms[i + 4] * y + xforms[i + 5];
             }
             break;
         default:
             SkFAIL("Unknown transform type.");
             break;
     }
 }