Include WebViewId into EmbedderMsg variants where possible (#35211)

`EmbedderMsg` was previously paired with an implicit
`Option<WebViewId>`, even though almost all variants were either always
`Some` or always `None`, depending on whether there was a `WebView
involved.

This patch adds the `WebViewId` to as many `EmbedderMsg` variants as
possible, so we can call their associated `WebView` delegate methods
without needing to check and unwrap the `Option`. In many cases, this
required more changes to plumb through the `WebViewId`.

Notably, all `Request`s now explicitly need a `WebView` or not, in order
to ensure that it is passed when appropriate.

Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

components/layout_thread_2020/lib.rs

@@ -16,7 +16,7 @@ use std::sync::{Arc, LazyLock};
 
 use app_units::Au;
 use base::cross_process_instant::CrossProcessInstant;
-use base::id::PipelineId;
+use base::id::{PipelineId, WebViewId};
 use base::Epoch;
 use embedder_traits::resources::{self, Resource};
 use euclid::default::{Point2D as UntypedPoint2D, Rect as UntypedRect, Size2D as UntypedSize2D};
@@ -105,6 +105,9 @@ pub struct LayoutThread {
     /// The ID of the pipeline that we belong to.
     id: PipelineId,
 
+    /// The webview that contains the pipeline we belong to.
+    webview_id: WebViewId,
+
     /// The URL of the pipeline that we belong to.
     url: ServoUrl,
 
@@ -169,18 +172,7 @@ pub struct LayoutFactoryImpl();
 
 impl LayoutFactory for LayoutFactoryImpl {
     fn create(&self, config: LayoutConfig) -> Box<dyn Layout> {
-        Box::new(LayoutThread::new(
-            config.id,
-            config.url,
-            config.is_iframe,
-            config.script_chan,
-            config.image_cache,
-            config.font_context,
-            config.time_profiler_chan,
-            config.compositor_api,
-            config.paint_time_metrics,
-            config.window_size,
-        ))
+        Box::new(LayoutThread::new(config))
     }
 }
 
@@ -476,23 +468,12 @@ impl Layout for LayoutThread {
     }
 }
 
-#[allow(clippy::too_many_arguments)]
 impl LayoutThread {
-    #[allow(clippy::too_many_arguments)]
-    fn new(
-        id: PipelineId,
-        url: ServoUrl,
-        is_iframe: bool,
-        script_chan: IpcSender<ConstellationControlMsg>,
-        image_cache: Arc<dyn ImageCache>,
-        font_context: Arc<FontContext>,
-        time_profiler_chan: profile_time::ProfilerChan,
-        compositor_api: CrossProcessCompositorApi,
-        paint_time_metrics: PaintTimeMetrics,
-        window_size: WindowSizeData,
-    ) -> LayoutThread {
+    fn new(config: LayoutConfig) -> LayoutThread {
         // Let webrender know about this pipeline by sending an empty display list.
-        compositor_api.send_initial_transaction(id.into());
+        config
+            .compositor_api
+            .send_initial_transaction(config.id.into());
 
         let mut font = Font::initial_values();
         let default_font_size = pref!(fonts_default_size);
@@ -507,23 +488,24 @@ impl LayoutThread {
         let device = Device::new(
             MediaType::screen(),
             QuirksMode::NoQuirks,
-            window_size.initial_viewport,
-            Scale::new(window_size.device_pixel_ratio.get()),
-            Box::new(LayoutFontMetricsProvider(font_context.clone())),
+            config.window_size.initial_viewport,
+            Scale::new(config.window_size.device_pixel_ratio.get()),
+            Box::new(LayoutFontMetricsProvider(config.font_context.clone())),
             ComputedValues::initial_values_with_font_override(font),
             // TODO: obtain preferred color scheme from embedder
             PrefersColorScheme::Light,
         );
 
         LayoutThread {
-            id,
-            url,
-            is_iframe,
-            script_chan: script_chan.clone(),
-            time_profiler_chan,
+            id: config.id,
+            webview_id: config.webview_id,
+            url: config.url,
+            is_iframe: config.is_iframe,
+            script_chan: config.script_chan.clone(),
+            time_profiler_chan: config.time_profiler_chan,
             registered_painters: RegisteredPaintersImpl(Default::default()),
-            image_cache,
-            font_context,
+            image_cache: config.image_cache,
+            font_context: config.font_context,
             first_reflow: Cell::new(true),
             generation: Cell::new(0),
             box_tree: Default::default(),
@@ -531,14 +513,14 @@ impl LayoutThread {
             // Epoch starts at 1 because of the initial display list for epoch 0 that we send to WR
             epoch: Cell::new(Epoch(1)),
             viewport_size: Size2D::new(
-                Au::from_f32_px(window_size.initial_viewport.width),
-                Au::from_f32_px(window_size.initial_viewport.height),
+                Au::from_f32_px(config.window_size.initial_viewport.width),
+                Au::from_f32_px(config.window_size.initial_viewport.height),
             ),
-            compositor_api,
+            compositor_api: config.compositor_api,
             scroll_offsets: Default::default(),
             stylist: Stylist::new(device, QuirksMode::NoQuirks),
             webrender_image_cache: Default::default(),
-            paint_time_metrics,
+            paint_time_metrics: config.paint_time_metrics,
             debug: opts::get().debug.clone(),
         }
     }
@@ -619,6 +601,7 @@ impl LayoutThread {
         };
 
         self.font_context.add_all_web_fonts_from_stylesheet(
+            self.webview_id,
             stylesheet,
             guard,
             self.stylist.device(),