Implement non-XR Gamepad discovery and input (#31200)

* Create embedder event to send to constellation

* Handle gamepad message in constellation, send to script thread

* Handle GamepadEvent in script thread and dispatch event to document

* Add missing Clones, fix event

* Add gamepad task source

* Adjust GamepadIndex type, remove unused imports

* Add internal getter for gamepads list

* Update gamepad new methods

* Handle gamepad connect and disconnect events

* Proto will be none, no need for HandleObject

* Initialize buttons and axes to standard mapping

* Adjust update type index types

* Update GamepadButton update function

* Adjust Gamepad mapping comments to match spec, add update logic

* Amend comment

* Update button and axis inputs on Updated event

* Add GilRs as gamepad backend in servoshell

* Add spec links, queue gamepad updates on task source

* ./mach fmt

* Fix comment length

* Split out button init, update spec comments

* Move gamepad event handling from document to global

* Map and normalize axes/button values

* Use std::time for gamepad timestamp

* Adjust gamepad handling in event loop

* Move button press/touch check into map+normalize function

- Small change but is more in line with spec

* ./mach fmt

* Update comment spec links and warning messages

* Doc comments -> regular comments

* Add window event handlers for gamepad connect/disconnect

* Adjust gamepad disconnect behavior

* Add missing TODO's, adjust gamepad/gamepadbutton list methods and formatting

* Update button handling from gilrs, add comments

* Enable gamepad pref during WPT tests and update expectations

* Update WPT expectations in meta-legacy-layout

components/script/script_thread.rs

@@ -75,8 +75,8 @@ use profile_traits::time::{self as profile_time, profile, ProfilerCategory};
 use script_layout_interface::message::{self, LayoutThreadInit, Msg, ReflowGoal};
 use script_traits::webdriver_msg::WebDriverScriptCommand;
 use script_traits::CompositorEvent::{
-    CompositionEvent, IMEDismissedEvent, KeyboardEvent, MouseButtonEvent, MouseMoveEvent,
-    ResizeEvent, TouchEvent, WheelEvent,
+    CompositionEvent, GamepadEvent, IMEDismissedEvent, KeyboardEvent, MouseButtonEvent,
+    MouseMoveEvent, ResizeEvent, TouchEvent, WheelEvent,
 };
 use script_traits::{
     AnimationTickType, CompositorEvent, ConstellationControlMsg, DiscardBrowsingContext,
@@ -152,6 +152,7 @@ use crate::task_manager::TaskManager;
 use crate::task_queue::{QueuedTask, QueuedTaskConversion, TaskQueue};
 use crate::task_source::dom_manipulation::DOMManipulationTaskSource;
 use crate::task_source::file_reading::FileReadingTaskSource;
+use crate::task_source::gamepad::GamepadTaskSource;
 use crate::task_source::history_traversal::HistoryTraversalTaskSource;
 use crate::task_source::media_element::MediaElementTaskSource;
 use crate::task_source::networking::NetworkingTaskSource;
@@ -568,6 +569,8 @@ pub struct ScriptThread {
 
     dom_manipulation_task_sender: Box<dyn ScriptChan>,
 
+    gamepad_task_sender: Box<dyn ScriptChan>,
+
     #[no_trace]
     media_element_task_sender: Sender<MainThreadScriptMsg>,
 
@@ -1354,6 +1357,7 @@ impl ScriptThread {
 
             chan: MainThreadScriptChan(chan.clone()),
             dom_manipulation_task_sender: boxed_script_sender.clone(),
+            gamepad_task_sender: boxed_script_sender.clone(),
             media_element_task_sender: chan.clone(),
             user_interaction_task_sender: chan.clone(),
             networking_task_sender: boxed_script_sender.clone(),
@@ -2858,6 +2862,10 @@ impl ScriptThread {
         DOMManipulationTaskSource(self.dom_manipulation_task_sender.clone(), pipeline_id)
     }
 
+    pub fn gamepad_task_source(&self, pipeline_id: PipelineId) -> GamepadTaskSource {
+        GamepadTaskSource(self.gamepad_task_sender.clone(), pipeline_id)
+    }
+
     pub fn media_element_task_source(&self, pipeline_id: PipelineId) -> MediaElementTaskSource {
         MediaElementTaskSource(self.media_element_task_sender.clone(), pipeline_id)
     }
@@ -3283,6 +3291,7 @@ impl ScriptThread {
         let task_manager = TaskManager::new(
             self.dom_manipulation_task_source(incomplete.pipeline_id),
             self.file_reading_task_source(incomplete.pipeline_id),
+            self.gamepad_task_source(incomplete.pipeline_id),
             self.history_traversal_task_source(incomplete.pipeline_id),
             self.media_element_task_source(incomplete.pipeline_id),
             self.networking_task_source(incomplete.pipeline_id),
@@ -3669,6 +3678,15 @@ impl ScriptThread {
                 };
                 document.dispatch_composition_event(composition_event);
             },
+
+            GamepadEvent(gamepad_event) => {
+                let window = match self.documents.borrow().find_window(pipeline_id) {
+                    Some(window) => window,
+                    None => return warn!("Message sent to closed pipeline {}.", pipeline_id),
+                };
+                let global = window.upcast::<GlobalScope>();
+                global.handle_gamepad_event(gamepad_event);
+            },
         }
 
         ScriptThread::set_user_interacting(false);