fonts: Simplify `FontContext` in two ways that affect the unit test (#33541)

This is done by no longer forwarding compositor-bound messages through
SystemFontService and making `FontContext` non-generic:

- Messages from the `FontContext` to the `Compositor` no longer need to be
  forwarded through the `SystemFontService`. Instead send these messages
  directly through the script IPC channel to the `Compositor`.

- Instead of adding a mock `SystemFontServiceProxy`, simply implement a
  mock `SystemFontService` on the other side of an IPC channel in the
  `font_context` unit test. This allows making `FontContext`
  non-generic, greatly simplifying the code. The extra complexity moves
  into the unit test.

These changes necessitate adding a new kind of `FontIdentifier`,
`FontIdentifier::Mock` due to the fact that local fonts have
platform-specific identifiers. This avoids having to pretend like the
system font service can have web fonts -- which was always a bit of a
hack.

These two changes are combined into one PR because they both require
extensive and similar chages in the font_context unit test which
dependended on the details of both of them.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

1 files changed, 15 insertions, 41 deletions

diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index 15438de42fe..7c44981600d 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -1101,59 +1101,33 @@ impl WebRenderFontApi for WebRenderFontApiCompositorProxy {
         flags: FontInstanceFlags,
     ) -> FontInstanceKey {
         let (sender, receiver) = unbounded();
-        self.0
-            .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
-                FontToCompositorMsg::AddFontInstance(font_key, size, flags, sender),
-            )));
+        self.0.send(CompositorMsg::Forwarded(
+            ForwardedToCompositorMsg::SystemFontService(FontToCompositorMsg::AddFontInstance(
+                font_key, size, flags, sender,
+            )),
+        ));
         receiver.recv().unwrap()
     }
 
     fn add_font(&self, data: Arc<IpcSharedMemory>, index: u32) -> FontKey {
         let (sender, receiver) = unbounded();
-        self.0
-            .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
-                FontToCompositorMsg::AddFont(sender, index, data),
-            )));
+        self.0.send(CompositorMsg::Forwarded(
+            ForwardedToCompositorMsg::SystemFontService(FontToCompositorMsg::AddFont(
+                sender, index, data,
+            )),
+        ));
         receiver.recv().unwrap()
     }
 
     fn add_system_font(&self, handle: NativeFontHandle) -> FontKey {
         let (sender, receiver) = unbounded();
-        self.0
-            .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
-                FontToCompositorMsg::AddSystemFont(sender, handle),
-            )));
+        self.0.send(CompositorMsg::Forwarded(
+            ForwardedToCompositorMsg::SystemFontService(FontToCompositorMsg::AddSystemFont(
+                sender, handle,
+            )),
+        ));
         receiver.recv().unwrap()
     }
-
-    fn forward_add_font_message(
-        &self,
-        data: Arc<IpcSharedMemory>,
-        font_index: u32,
-        result_sender: IpcSender<FontKey>,
-    ) {
-        let (sender, receiver) = unbounded();
-        self.0
-            .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
-                FontToCompositorMsg::AddFont(sender, font_index, data),
-            )));
-        let _ = result_sender.send(receiver.recv().unwrap());
-    }
-
-    fn forward_add_font_instance_message(
-        &self,
-        font_key: FontKey,
-        size: f32,
-        flags: FontInstanceFlags,
-        result_sender: IpcSender<FontInstanceKey>,
-    ) {
-        let (sender, receiver) = unbounded();
-        self.0
-            .send(CompositorMsg::Forwarded(ForwardedToCompositorMsg::Font(
-                FontToCompositorMsg::AddFontInstance(font_key, size, flags, sender),
-            )));
-        let _ = result_sender.send(receiver.recv().unwrap());
-    }
 }
 
 #[derive(Clone)]