Extract subpixel offsets from composited layer transforms when possible.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index d74a3b6ff7979a64d2b2b21371d6b1125a550597..7be251f9e3f9440d88f13ce15d9ee4f9cb2e8d27 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -569,10 +569,16 @@ void PictureLayerImpl::UpdateRasterSource(
   // tilings that are going to disappear on the pending tree (if scale changed).
   // But that would also be more complicated, so we just do it here for now.
   if (pending_set) {
+      LOG(ERROR) << "pending_set: " << raster_source_.get();
+
     tilings_->UpdateTilingsToCurrentRasterSourceForActivation(
         raster_source_, pending_set, invalidation_, MinimumContentsScale(),
         MaximumContentsScale());
   } else {
+   
+    LOG(ERROR) << "SetSubpixelOffset: " << raster_source_.get() << ": " << subpixel_offset_.ToString() << ": " << raster_source_->GetSize().ToString();
+    LOG(ERROR) << "DrawsContent: " << DrawsContent();
+    raster_source_->SetSubpixelOffset(subpixel_offset_);
     tilings_->UpdateTilingsToCurrentRasterSourceForCommit(
         raster_source_, invalidation_, MinimumContentsScale(),
         MaximumContentsScale());