servo: Merge #15679 - Implement cross-thread postMessage (from asajeffrey:script-postMessage-xorigin); r=emilio

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This PR implements cross-thread postMessage,

It builds on #15438 and #15478, only the last commit is part of this PR.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] There are tests for these changes

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Source-Repo: https://github.com/servo/servo
Source-Revision: 1caf8a71dcdb9d749ad2d2c9d82fe0d913d7e17c

servo/components/script_traits/lib.rs

@@ -63,6 +63,7 @@ use net_traits::storage_thread::StorageType;
 use profile_traits::mem;
 use profile_traits::time as profile_time;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
+use servo_url::ImmutableOrigin;
 use servo_url::ServoUrl;
 use std::collections::HashMap;
 use std::fmt;
@@ -239,6 +240,8 @@ pub enum ConstellationControlMsg {
     /// Notifies script thread that a url should be loaded in this iframe.
     /// PipelineId is for the parent, FrameId is for the actual frame.
     Navigate(PipelineId, FrameId, LoadData, bool),
+    /// Post a message to a given window.
+    PostMessage(PipelineId, Option<ImmutableOrigin>, Vec<u8>),
     /// Requests the script thread forward a mozbrowser event to an iframe it owns,
     /// or to the window if no child frame id is provided.
     MozBrowserEvent(PipelineId, Option<FrameId>, MozBrowserEvent),
@@ -297,6 +300,7 @@ impl fmt::Debug for ConstellationControlMsg {
             ChangeFrameVisibilityStatus(..) => "ChangeFrameVisibilityStatus",
             NotifyVisibilityChange(..) => "NotifyVisibilityChange",
             Navigate(..) => "Navigate",
+            PostMessage(..) => "PostMessage",
             MozBrowserEvent(..) => "MozBrowserEvent",
             UpdatePipelineId(..) => "UpdatePipelineId",
             FocusIFrame(..) => "FocusIFrame",

servo/components/script_traits/script_msg.rs

@@ -23,6 +23,7 @@ use msg::constellation_msg::{Key, KeyModifiers, KeyState};
 use net_traits::CoreResourceMsg;
 use net_traits::storage_thread::StorageType;
 use offscreen_gl_context::{GLContextAttributes, GLLimits};
+use servo_url::ImmutableOrigin;
 use servo_url::ServoUrl;
 use style_traits::CSSPixel;
 use style_traits::cursor::Cursor;
@@ -93,6 +94,8 @@ pub enum ScriptMsg {
     /// A new load has been requested, with an option to replace the current entry once loaded
     /// instead of adding a new entry.
     LoadUrl(PipelineId, LoadData, bool),
+    /// Post a message to the currently active window of a given browsing context.
+    PostMessage(FrameId, Option<ImmutableOrigin>, Vec<u8>),
     /// Dispatch a mozbrowser event to the parent of this pipeline.
     /// The first PipelineId is for the parent, the second is for the originating pipeline.
     MozBrowserEvent(PipelineId, PipelineId, MozBrowserEvent),