Use variable length key (rather than accumulated matrix) as save layer hoisting key

tests/RecordReplaceDrawTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #if SK_SUPPORT_GPU
 
 #include "Test.h"
@@ skipping 97 matching lines @@
 
         SkAutoTDelete<SkPaint> paint(SkNEW(SkPaint));
         canvas->saveLayer(NULL, paint);
         canvas->clear(SK_ColorRED);
         canvas->restore();
         canvas->drawRect(SkRect::MakeWH(SkIntToScalar(kWidth / 2), SkIntToScalar(kHeight / 2)),
                          SkPaint());
         pic.reset(recorder.endRecording());
     }
 
+    int key[1] = { 0 };
+
     GrReplacements replacements;
-    GrReplacements::ReplacementInfo* ri = replacements.newReplacement(pic->uniqueID(),
-                                                                      0, SkMatrix::I());
+    GrReplacements::ReplacementInfo* ri = replacements.newReplacement(pic->uniqueID(), 
+                                                                      SkMatrix::I(), key, 1);
     ri->fStop = 2;
     ri->fPos.set(0, 0);
     ri->fImage = make_image(SK_ColorRED);
     ri->fPaint = SkNEW(SkPaint);
     ri->fSrcRect = SkIRect::MakeWH(kWidth, kHeight);
 
     SkAutoTUnref<SkBBoxHierarchy> bbh;
 
     SkRecord rerecord;
     SkRecorder canvas(&rerecord, kWidth, kHeight);
     GrRecordReplaceDraw(pic, &canvas, &replacements, SkMatrix::I(), NULL/*callback*/);
 
     REPORTER_ASSERT(r, 7 == rerecord.count());
     assert_type<SkRecords::Save>(r, rerecord, 0);
     assert_type<SkRecords::Save>(r, rerecord, 1);
     assert_type<SkRecords::SetMatrix>(r, rerecord, 2);
     assert_type<SkRecords::DrawImageRect>(r, rerecord, 3);
     assert_type<SkRecords::Restore>(r, rerecord, 4);
     assert_type<SkRecords::DrawRect>(r, rerecord, 5);
     assert_type<SkRecords::Restore>(r, rerecord, 6);
 }
 
 DEF_TEST(RecordReplaceDraw_Replace, r)        { test_replacements(r, false); }
 DEF_TEST(RecordReplaceDraw_ReplaceWithBBH, r) { test_replacements(r, true); }
 
 #endif