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>

components/fonts/platform/freetype/android/font_list.rs

@@ -19,7 +19,8 @@ use style::Atom;
 
 use super::xml::{Attribute, Node};
 use crate::{
-    FallbackFontSelectionOptions, FontTemplate, FontTemplateDescriptor, LowercaseFontFamilyName,
+    FallbackFontSelectionOptions, FontIdentifier, FontTemplate, FontTemplateDescriptor,
+    LowercaseFontFamilyName,
 };
 
 static FONT_LIST: LazyLock<FontList> = LazyLock::new(|| FontList::new());
@@ -491,9 +492,10 @@ where
             None => StyleFontStyle::NORMAL,
         };
         let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
-        callback(FontTemplate::new_for_local_font(
-            local_font_identifier,
+        callback(FontTemplate::new(
+            FontIdentifier::Local(local_font_identifier),
             descriptor,
+            None,
         ));
     };
 

components/fonts/platform/freetype/font_list.rs

@@ -36,7 +36,10 @@ use super::c_str_to_string;
 use crate::font::map_platform_values_to_style_values;
 use crate::font_template::{FontTemplate, FontTemplateDescriptor};
 use crate::platform::add_noto_fallback_families;
-use crate::{EmojiPresentationPreference, FallbackFontSelectionOptions, LowercaseFontFamilyName};
+use crate::{
+    EmojiPresentationPreference, FallbackFontSelectionOptions, FontIdentifier,
+    LowercaseFontFamilyName,
+};
 
 /// An identifier for a local font on systems using Freetype.
 #[derive(Clone, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
@@ -155,9 +158,10 @@ where
             };
             let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
 
-            callback(FontTemplate::new_for_local_font(
-                local_font_identifier,
+            callback(FontTemplate::new(
+                FontIdentifier::Local(local_font_identifier),
                 descriptor,
+                None,
             ))
         }
 

components/fonts/platform/freetype/ohos/font_list.rs

@@ -22,7 +22,7 @@ use style::Atom;
 use unicode_script::Script;
 
 use crate::{
-    EmojiPresentationPreference, FallbackFontSelectionOptions, FontTemplate,
+    EmojiPresentationPreference, FallbackFontSelectionOptions, FontIdentifier, FontTemplate,
     FontTemplateDescriptor, LowercaseFontFamilyName,
 };
 
@@ -492,9 +492,10 @@ where
             None => StyleFontStyle::NORMAL,
         };
         let descriptor = FontTemplateDescriptor::new(weight, stretch, style);
-        callback(FontTemplate::new_for_local_font(
-            local_font_identifier,
+        callback(FontTemplate::new(
+            FontIdentifier::Local(local_font_identifier),
             descriptor,
+            None,
         ));
     };
 

components/fonts/platform/macos/core_text_font_cache.rs

@@ -86,7 +86,7 @@ impl CoreTextFontCache {
 
                 core_text::font::new_from_descriptor(&descriptor, clamped_pt_size)
             },
-            FontIdentifier::Web(_) => {
+            FontIdentifier::Web(_) | FontIdentifier::Mock(_) => {
                 let provider = CGDataProvider::from_buffer(data);
                 let cgfont = CGFont::from_data_provider(provider).ok()?;
                 core_text::font::new_from_CGFont(&cgfont, clamped_pt_size)

components/fonts/platform/macos/font_list.rs

@@ -18,7 +18,7 @@ use webrender_api::NativeFontHandle;
 use crate::platform::add_noto_fallback_families;
 use crate::platform::font::CoreTextFontTraitsMapping;
 use crate::{
-    EmojiPresentationPreference, FallbackFontSelectionOptions, FontTemplate,
+    EmojiPresentationPreference, FallbackFontSelectionOptions, FontIdentifier, FontTemplate,
     FontTemplateDescriptor, LowercaseFontFamilyName,
 };
 
@@ -85,7 +85,11 @@ where
                     postscript_name: Atom::from(family_descriptor.font_name()),
                     path: Atom::from(path),
                 };
-                callback(FontTemplate::new_for_local_font(identifier, descriptor));
+                callback(FontTemplate::new(
+                    FontIdentifier::Local(identifier),
+                    descriptor,
+                    None,
+                ));
             }
         }
     }

components/fonts/platform/windows/font_list.rs

@@ -14,7 +14,7 @@ use style::values::computed::{FontStyle as StyleFontStyle, FontWeight as StyleFo
 use style::values::specified::font::FontStretchKeyword;
 
 use crate::{
-    EmojiPresentationPreference, FallbackFontSelectionOptions, FontTemplate,
+    EmojiPresentationPreference, FallbackFontSelectionOptions, FontIdentifier, FontTemplate,
     FontTemplateDescriptor, LowercaseFontFamilyName,
 };
 
@@ -78,9 +78,10 @@ where
             let local_font_identifier = LocalFontIdentifier {
                 font_descriptor: Arc::new(font.to_descriptor()),
             };
-            callback(FontTemplate::new_for_local_font(
-                local_font_identifier,
+            callback(FontTemplate::new(
+                FontIdentifier::Local(local_font_identifier),
                 template_descriptor,
+                None,
             ))
         }
     }