Attempt to combine batches in forward direction before flush

dm/DMSrcSink.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 "DMSrcSink.h"
 #include "SkAndroidCodec.h"
 #include "SkCodec.h"
@@ skipping 851 matching lines @@
     , fSampleCount(samples)
     , fUseDIText(diText)
     , fThreaded(threaded) {}
 
 void PreAbandonGpuContextErrorHandler(SkError, void*) {}
 
 DEFINE_bool(imm, false, "Run gpu configs in immediate mode.");
 DEFINE_bool(batchClip, false, "Clip each GrBatch to its device bounds for testing.");
 DEFINE_bool(batchBounds, false, "Draw a wireframe bounds of each GrBatch.");
 DEFINE_int32(batchLookback, -1, "Maximum GrBatch lookback for combining, negative means default.");
+DEFINE_int32(batchLookahead, -1, "Maximum GrBatch lookahead for combining, negative means "
+                                 "default.");
 
 Error GPUSink::draw(const Src& src, SkBitmap* dst, SkWStream*, SkString* log) const {
     GrContextOptions grOptions;
     grOptions.fImmediateMode = FLAGS_imm;
     grOptions.fClipBatchToBounds = FLAGS_batchClip;
     grOptions.fDrawBatchBounds = FLAGS_batchBounds;
     grOptions.fMaxBatchLookback = FLAGS_batchLookback;
+    grOptions.fMaxBatchLookahead = FLAGS_batchLookahead;
 
     src.modifyGrContextOptions(&grOptions);
 
     GrContextFactory factory(grOptions);
     const SkISize size = src.size();
     const SkImageInfo info =
         SkImageInfo::Make(size.width(), size.height(), kN32_SkColorType, kPremul_SkAlphaType);
 #if SK_SUPPORT_GPU
     const int maxDimension = factory.getContextInfo(fContextType, fContextOptions).
             fGrContext->caps()->maxTextureSize();
@@ skipping 533 matching lines @@
             skr.visit<void>(i, drawsAsSingletonPictures);
         }
         SkAutoTUnref<SkPicture> macroPic(macroRec.endRecordingAsPicture());
 
         canvas->drawPicture(macroPic);
         return check_against_reference(bitmap, src, fSink);
     });
 }
 
 }  // namespace DM