Add SaveLayer-Draw-Restore optimization.

src/record/SkRecordOpts.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkRecordOpts_DEFINED
 #define SkRecordOpts_DEFINED
 
 #include "SkRecord.h"
 
 // Run all optimizations in recommended order.
 void SkRecordOptimize(SkRecord*);
 
 
 // Turns logical no-op Save-[non-drawing command]*-Restore patterns into actual no-ops.
 void SkRecordNoopSaveRestores(SkRecord*);
 
+// For some SaveLayer-[drawing command]-Restore patterns, merge the SaveLayer's alpha into the
+// draw, and no-op the SaveLayer and Restore.
+void SkRecordNoopSaveLayerDrawRestores(SkRecord*);
+
 // Annotates PushCull commands with the relative offset of their paired PopCull.
 void SkRecordAnnotateCullingPairs(SkRecord*);
 
 // Convert DrawPosText to DrawPosTextH when all the Y coordinates are equal.
 void SkRecordReduceDrawPosTextStrength(SkRecord*);
 
 // Calculate min and max Y bounds for DrawPosTextH commands, for use with SkCanvas::quickRejectY.
 void SkRecordBoundDrawPosTextH(SkRecord*);
 
 #endif//SkRecordOpts_DEFINED