diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 654bedbf941..3112540c2a9 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -282,8 +282,8 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 response_channel.send(());
             }
 
-            (Msg::CreateOrUpdateRootLayer(layer_properties), ShutdownState::NotShuttingDown) => {
-                self.create_or_update_root_layer(layer_properties);
+            (Msg::CreateOrUpdateBaseLayer(layer_properties), ShutdownState::NotShuttingDown) => {
+                self.create_or_update_base_layer(layer_properties);
             }
 
             (Msg::CreateOrUpdateDescendantLayer(layer_properties),
@@ -539,24 +539,24 @@ impl<Window: WindowMethods> IOCompositor<Window> {
         }
     }
 
-    fn create_or_update_root_layer(&mut self, layer_properties: LayerProperties) {
-        let need_new_root_layer = !self.update_layer_if_exists(layer_properties);
-        if need_new_root_layer {
+    fn create_or_update_base_layer(&mut self, layer_properties: LayerProperties) {
+        let need_new_base_layer = !self.update_layer_if_exists(layer_properties);
+        if need_new_base_layer {
             let root_layer = self.find_pipeline_root_layer(layer_properties.pipeline_id);
             root_layer.update_layer_except_bounds(layer_properties);
 
             let root_layer_pipeline = root_layer.extra_data.borrow().pipeline.clone();
-            let first_child = CompositorData::new_layer(
+            let base_layer = CompositorData::new_layer(
                 root_layer_pipeline.clone(),
                 layer_properties,
                 WantsScrollEventsFlag::DoesntWantScrollEvents,
                 opts::get().tile_size);
 
-            // Add the first child / base layer to the front of the child list, so that
-            // child iframe layers are painted on top of the base layer. These iframe
-            // layers were added previously when creating the layer tree skeleton in
-            // create_frame_tree_root_layers.
-            root_layer.children().insert(0, first_child);
+            // Add the base layer to the front of the child list, so that child
+            // iframe layers are painted on top of the base layer. These iframe
+            // layers were added previously when creating the layer tree
+            // skeleton in create_frame_tree_root_layers.
+            root_layer.children().insert(0, base_layer);
         }
 
         self.scroll_layer_to_fragment_point_if_necessary(layer_properties.pipeline_id,
diff --git a/components/compositing/compositor_task.rs b/components/compositing/compositor_task.rs
index 969c1ef0c53..6ceda64cbaf 100644
--- a/components/compositing/compositor_task.rs
+++ b/components/compositing/compositor_task.rs
@@ -147,7 +147,7 @@ impl PaintListener for Box<CompositorProxy+'static+Send> {
         for metadata in metadata.iter() {
             let layer_properties = LayerProperties::new(pipeline_id, epoch, metadata);
             if first {
-                self.send(Msg::CreateOrUpdateRootLayer(layer_properties));
+                self.send(Msg::CreateOrUpdateBaseLayer(layer_properties));
                 first = false
             } else {
                 self.send(Msg::CreateOrUpdateDescendantLayer(layer_properties));
@@ -183,7 +183,7 @@ pub enum Msg {
 
     /// Tells the compositor to create the root layer for a pipeline if necessary (i.e. if no layer
     /// with that ID exists).
-    CreateOrUpdateRootLayer(LayerProperties),
+    CreateOrUpdateBaseLayer(LayerProperties),
     /// Tells the compositor to create a descendant layer for a pipeline if necessary (i.e. if no
     /// layer with that ID exists).
     CreateOrUpdateDescendantLayer(LayerProperties),
@@ -226,7 +226,7 @@ impl Show for Msg {
             Msg::Exit(..) => write!(f, "Exit"),
             Msg::ShutdownComplete(..) => write!(f, "ShutdownComplete"),
             Msg::GetGraphicsMetadata(..) => write!(f, "GetGraphicsMetadata"),
-            Msg::CreateOrUpdateRootLayer(..) => write!(f, "CreateOrUpdateRootLayer"),
+            Msg::CreateOrUpdateBaseLayer(..) => write!(f, "CreateOrUpdateBaseLayer"),
             Msg::CreateOrUpdateDescendantLayer(..) => write!(f, "CreateOrUpdateDescendantLayer"),
             Msg::SetLayerOrigin(..) => write!(f, "SetLayerOrigin"),
             Msg::ScrollFragmentPoint(..) => write!(f, "ScrollFragmentPoint"),
diff --git a/components/compositing/headless.rs b/components/compositing/headless.rs
index 1ae584ff5ea..8b58d727292 100644
--- a/components/compositing/headless.rs
+++ b/components/compositing/headless.rs
@@ -98,7 +98,7 @@ impl CompositorEventListener for NullCompositor {
             // we'll notice and think about whether it needs a response, like
             // SetFrameTree.
 
-            Msg::CreateOrUpdateRootLayer(..) |
+            Msg::CreateOrUpdateBaseLayer(..) |
             Msg::CreateOrUpdateDescendantLayer(..) |
             Msg::SetLayerOrigin(..) |
             Msg::AssignPaintedBuffers(..) |