Defer saves() until they're needed

tests/PictureBBHTest.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.
  */
 
 #include "SkCanvas.h"
 #include "SkBBoxHierarchy.h"
 #include "SkPaint.h"
@@ skipping 101 matching lines @@
     SkAutoTUnref<SkPicture> srcPic(src.endRecording());
 
     // A target canvas with an empty clip.
     SkCanvas* c = dst.beginRecording(1,1, NULL);
         c->clipRect(SkRect::MakeEmpty());
         srcPic->playback(c);
     SkAutoTUnref<SkPicture> dstPic(dst.endRecording());
 
     // Should be Clip - Save - Clear - Restore.
     // Buggy implementations might return 1 (just Clip) or 3 (Clip - Save - Restore).
-    REPORTER_ASSERT(r, dstPic->approximateOpCount() == 4);
+    // TODO: can we just search that it contains "clear"? <reed>
+    REPORTER_ASSERT(r, dstPic->approximateOpCount() == 4 || dstPic->approximateOpCount() == 2);
 }
 
 DEF_TEST(PictureBBH_Clear, r) {
     test_clear(r, NULL);
 
     SkTileGridFactory::TileGridInfo grid = { {1,1}, {0,0}, {0,0} };
     SkTileGridFactory tilegrid(grid);
     test_clear(r, &tilegrid);
 
     SkRTreeFactory rtree;
     test_clear(r, &rtree);
 }