cc: Don't swap PictureLayerTilingSet on activate.

cc/resources/picture_layer_tiling_unittest.cc

Index: cc/resources/picture_layer_tiling_unittest.cc
diff --git a/cc/resources/picture_layer_tiling_unittest.cc b/cc/resources/picture_layer_tiling_unittest.cc
index 9190b98e48dd5e4662adfbd0ce5b256fb45ac5f0..abcdfaa501f85535b17eafeb50d68063d867639b 100644
--- a/cc/resources/picture_layer_tiling_unittest.cc
+++ b/cc/resources/picture_layer_tiling_unittest.cc
@@ -1369,8 +1369,8 @@ TEST_F(PictureLayerTilingIteratorTest, AddTilingsToMatchScale) {
   // Add the same tilings to the pending set.
   auto pending_set = PictureLayerTilingSet::Create(&client_);
   Region invalidation;
-  pending_set->SyncTilings(*active_set, layer_bounds, invalidation, 0.f,
-                           client_.raster_source());
+  pending_set->SyncTilingsForTesting(*active_set, layer_bounds, invalidation,
+                                     0.f, client_.raster_source());
 
   // The pending tiling starts with no tiles.
   VerifyTiles(pending_set->tiling_at(0), 1.f, gfx::Rect(layer_bounds),