Auto merge of #14099 - emilio:canvas-data, r=nox

canvas: Cleanup CanvasData and layout and script messages.

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components/script/dom/htmlcanvaselement.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use canvas_traits::{CanvasMsg, FromLayoutMsg, CanvasData};
+use canvas_traits::{CanvasMsg, FromScriptMsg};
 use dom::attr::Attr;
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::CanvasRenderingContext2DMethods;
@@ -202,16 +202,17 @@ impl HTMLCanvasElement {
 
         let data = if let Some(renderer) = self.ipc_renderer() {
             let (sender, receiver) = ipc::channel().unwrap();
-            let msg = CanvasMsg::FromLayout(FromLayoutMsg::SendData(sender));
+            let msg = CanvasMsg::FromScript(FromScriptMsg::SendPixels(sender));
             renderer.send(msg).unwrap();
 
             match receiver.recv().unwrap() {
-                CanvasData::Pixels(pixel_data)
-                    => pixel_data.image_data.to_vec(),
-                CanvasData::WebGL(_)
-                    // TODO(emilio): Not sure if WebGL canvas is required for 2d spec,
-                    // but I think it's not.
-                    => return None,
+                Some(pixels) => pixels,
+                None => {
+                    // TODO(emilio, #14109): Not sure if WebGL canvas is
+                    // required for 2d spec, but I think it's not, if so, make
+                    // this return a readback from the GL context.
+                    return None;
+                }
             }
         } else {
             repeat(0xffu8).take((size.height as usize) * (size.width as usize) * 4).collect()