cc: Add some useful layer data to traces.

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 1205e076a0f4b072cd31ad4e489fffad8e2294c3..32f8d92baf73e77713c04b36d6ecc4ddb4facf0c 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -1411,6 +1411,14 @@ void PictureLayerImpl::AsValueInto(base::debug::TracedValue* state) const {
   tilings_->AsValueInto(state);
   state->EndArray();
 
+  state->BeginArray("tile_priority_rect");
+  MathUtil::AddToTracedValue(GetViewportForTilePriorityInContentSpace(), state);
+  state->EndArray();
+
+  state->BeginArray("visible_rect");
+  MathUtil::AddToTracedValue(visible_content_rect(), state);
+  state->EndArray();
+
   state->BeginArray("pictures");
   pile_->AsValueInto(state);
   state->EndArray();