fonts: Clean up messaging during web fonts loads (#32332)

Instead of sending a message to the script thread via IPC when a web
font loads and then sending another, just give the `FontContext` a
callback that send a single message to the script thread. This moves all
the cache invalidation internally into `FontContext` as well.

Additionally, the unused LayoutControlMessage::ExitNow enum variant is
removed.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Mukilan Thiyagarajan <mukilan@igalia.com>

3 files changed, 5 insertions, 9 deletions

diff --git a/components/shared/gfx/lib.rs b/components/shared/gfx/lib.rs
index e5699f2504a..032dcfd19e0 100644
--- a/components/shared/gfx/lib.rs
+++ b/components/shared/gfx/lib.rs
@@ -4,6 +4,8 @@
 
 #![deny(unsafe_code)]
 
+use std::sync::Arc;
+
 use malloc_size_of_derive::MallocSizeOf;
 use range::{int_range_index, RangeIndex};
 use serde::{Deserialize, Serialize};
@@ -14,3 +16,5 @@ int_range_index! {
     /// the middle of a glyph.
     struct ByteIndex(isize)
 }
+
+pub type WebFontLoadFinishedCallback = Arc<dyn Fn(bool) + Send + Sync + 'static>;
diff --git a/components/shared/script/lib.rs b/components/shared/script/lib.rs
index 16f1e07710d..931e34c2a2b 100644
--- a/components/shared/script/lib.rs
+++ b/components/shared/script/lib.rs
@@ -113,8 +113,6 @@ impl UntrustedNodeAddress {
 /// Messages sent to layout from the constellation and/or compositor.
 #[derive(Debug, Deserialize, Serialize)]
 pub enum LayoutControlMsg {
-    /// Requests that this layout clean up before exit.
-    ExitNow,
     /// Tells layout about the new scrolling offsets of each scrollable stacking context.
     SetScrollStates(Vec<ScrollState>),
     /// Send the paint time for a specific epoch to layout.
@@ -395,8 +393,6 @@ pub enum ConstellationControlMsg {
     SetWebGPUPort(IpcReceiver<WebGPUMsg>),
     /// A mesage for a layout from the constellation.
     ForLayoutFromConstellation(LayoutControlMsg, PipelineId),
-    /// A message for a layout from the font cache.
-    ForLayoutFromFontCache(PipelineId),
 }
 
 impl fmt::Debug for ConstellationControlMsg {
@@ -436,7 +432,6 @@ impl fmt::Debug for ConstellationControlMsg {
             MediaSessionAction(..) => "MediaSessionAction",
             SetWebGPUPort(..) => "SetWebGPUPort",
             ForLayoutFromConstellation(..) => "ForLayoutFromConstellation",
-            ForLayoutFromFontCache(..) => "ForLayoutFromFontCache",
         };
         write!(formatter, "ConstellationControlMsg::{}", variant)
     }
diff --git a/components/shared/script_layout/lib.rs b/components/shared/script_layout/lib.rs
index a15f0be9bde..b65d42d1731 100644
--- a/components/shared/script_layout/lib.rs
+++ b/components/shared/script_layout/lib.rs
@@ -179,10 +179,7 @@ pub trait LayoutFactory: Send + Sync {
 
 pub trait Layout {
     /// Handle a single message from the Constellation.
-    fn handle_constellation_msg(&mut self, msg: LayoutControlMsg);
-
-    /// Handle a a single mesasge from the FontCacheThread.
-    fn handle_font_cache_msg(&mut self);
+    fn handle_constellation_message(&mut self, msg: LayoutControlMsg);
 
     /// Get a reference to this Layout's Stylo `Device` used to handle media queries and
     /// resolve font metrics.