cc: Don't cleanup the pending twin's low res tiling.

cc/resources/picture_layer_tiling_set.cc

Index: cc/resources/picture_layer_tiling_set.cc
diff --git a/cc/resources/picture_layer_tiling_set.cc b/cc/resources/picture_layer_tiling_set.cc
index d292d83fab2a53d05ba39d7ca579e3db11c2c0cc..9967868900ef3d9e049e5df3acb1daac2f57dccd 100644
--- a/cc/resources/picture_layer_tiling_set.cc
+++ b/cc/resources/picture_layer_tiling_set.cc
@@ -109,12 +109,8 @@ void PictureLayerTilingSet::SetCanUseLCDText(bool can_use_lcd_text) {
 }
 
 PictureLayerTiling* PictureLayerTilingSet::AddTiling(float contents_scale) {
-  for (size_t i = 0; i < tilings_.size(); ++i) {
-    // TODO(enne): temporary sanity CHECK for http://crbug.com/358350.
-    // If a duplicate tiling gets added, then many assumptions in
-    // PictureLayerImpl fail.
-    CHECK_NE(tilings_[i]->contents_scale(), contents_scale);
-  }
+  for (size_t i = 0; i < tilings_.size(); ++i)
+    DCHECK_NE(tilings_[i]->contents_scale(), contents_scale);
 
   tilings_.push_back(PictureLayerTiling::Create(contents_scale,
                                                 layer_bounds_,