Improve gpu tracing when applying markers directly to gpu target

src/gpu/GrTraceMarker.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.
  */
 
 #include "SkTDArray.h"
 
@@ skipping 37 matching lines @@
     int count() const;
 
     /**
      * First sorts fMarkerArray and returns a string of the format
      * MarkerName1(#,#,...)%MarkerName2(#,#,...):... where MarkerName is the
      * marker string used in the TraceMarker and the (#,#,..) is a list of instance
      * id's for the the given marker string
      */
     SkString toString() const;
 
+    SkString toStringLast() const;
+
     class Iter;
 
     Iter begin() const;
 
     Iter end() const;
 
 private:
     mutable SkTDArray<GrGpuTraceMarker> fMarkerArray;
 };
 
@@ skipping 21 matching lines @@
     Iter(const GrTraceMarkerSet* markers, int index)
             : fMarkers(markers), fCurrentIndex(index) {
         SkASSERT(markers);
     }
 
     const GrTraceMarkerSet* fMarkers;
     int fCurrentIndex;
 };
 
 #endif