Synchronize dispatch_actions in WebDriver (#36932)

Implement missing synchronization in `dispatch_actions` of `WebDriver`.
https://w3c.github.io/webdriver/#dispatching-actions

> The user agent event loop has spun enough times to process the DOM
events generated by the last invocation of the >[dispatch tick
actions](https://w3c.github.io/webdriver/#dfn-dispatch-tick-actions)
steps.

- Add a way for `ScriptThread` to notify `WebDriver` about the
completion of input commands.
- Add a `webdriver_id` field for `InputEvent`. `ScriptThread` uses it to
distinguish WebDriver events and sends notification.

Tests:
`./mach test-wpt --product servodriver -r
tests\wpt\tests\webdriver\tests\classic\element_click\events.py` pass if
`hit_testing` pass. Check
[issue](https://github.com/servo/servo/issues/36676#issuecomment-2882917136)

cc: @xiaochengh

---------

Signed-off-by: batu_hoang <longvatrong111@gmail.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Martin Robinson <mrobinson@igalia.com>

components/shared/compositing/lib.rs

@@ -10,6 +10,7 @@ use base::id::{PipelineId, WebViewId};
 use crossbeam_channel::Sender;
 use embedder_traits::{
     AnimationState, EventLoopWaker, MouseButton, MouseButtonAction, TouchEventResult,
+    WebDriverMessageId,
 };
 use euclid::Rect;
 use ipc_channel::ipc::IpcSender;
@@ -101,9 +102,16 @@ pub enum CompositorMsg {
     /// The load of a page has completed
     LoadComplete(WebViewId),
     /// WebDriver mouse button event
-    WebDriverMouseButtonEvent(WebViewId, MouseButtonAction, MouseButton, f32, f32),
+    WebDriverMouseButtonEvent(
+        WebViewId,
+        MouseButtonAction,
+        MouseButton,
+        f32,
+        f32,
+        WebDriverMessageId,
+    ),
     /// WebDriver mouse move event
-    WebDriverMouseMoveEvent(WebViewId, f32, f32),
+    WebDriverMouseMoveEvent(WebViewId, f32, f32, WebDriverMessageId),
     // Webdriver wheel scroll event
     WebDriverWheelScrollEvent(WebViewId, f32, f32, f64, f64),
 

components/shared/constellation/from_script_message.rs

@@ -17,6 +17,7 @@ use devtools_traits::{DevtoolScriptControlMsg, ScriptToDevtoolsControlMsg, Worke
 use embedder_traits::{
     AnimationState, EmbedderMsg, FocusSequenceNumber, JSValue, JavaScriptEvaluationError,
     JavaScriptEvaluationId, MediaSessionEvent, TouchEventResult, ViewportDetails,
+    WebDriverMessageId,
 };
 use euclid::default::Size2D as UntypedSize2D;
 use http::{HeaderMap, Method};
@@ -652,6 +653,8 @@ pub enum ScriptToConstellationMessage {
         JavaScriptEvaluationId,
         Result<JSValue, JavaScriptEvaluationError>,
     ),
+    /// Notify the completion of a webdriver command.
+    WebDriverInputComplete(WebDriverMessageId),
 }
 
 impl fmt::Debug for ScriptToConstellationMessage {

components/shared/embedder/input_events.rs

@@ -8,6 +8,8 @@ use malloc_size_of_derive::MallocSizeOf;
 use serde::{Deserialize, Serialize};
 use webrender_api::units::DevicePoint;
 
+use crate::WebDriverMessageId;
+
 /// An input event that is sent from the embedder to Servo.
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub enum InputEvent {
@@ -42,6 +44,38 @@ impl InputEvent {
             InputEvent::Wheel(event) => Some(event.point),
         }
     }
+
+    pub fn webdriver_message_id(&self) -> Option<WebDriverMessageId> {
+        match self {
+            InputEvent::EditingAction(..) => None,
+            InputEvent::Gamepad(..) => None,
+            InputEvent::Ime(..) => None,
+            InputEvent::Keyboard(..) => None,
+            InputEvent::MouseButton(event) => event.webdriver_id,
+            InputEvent::MouseMove(event) => event.webdriver_id,
+            InputEvent::Touch(..) => None,
+            InputEvent::Wheel(..) => None,
+        }
+    }
+
+    pub fn with_webdriver_message_id(self, webdriver_id: Option<WebDriverMessageId>) -> Self {
+        match self {
+            InputEvent::EditingAction(..) => {},
+            InputEvent::Gamepad(..) => {},
+            InputEvent::Ime(..) => {},
+            InputEvent::Keyboard(..) => {},
+            InputEvent::MouseButton(mut event) => {
+                event.webdriver_id = webdriver_id;
+            },
+            InputEvent::MouseMove(mut event) => {
+                event.webdriver_id = webdriver_id;
+            },
+            InputEvent::Touch(..) => {},
+            InputEvent::Wheel(..) => {},
+        };
+
+        self
+    }
 }
 
 #[derive(Clone, Copy, Debug, Deserialize, Serialize)]
@@ -49,6 +83,18 @@ pub struct MouseButtonEvent {
     pub action: MouseButtonAction,
     pub button: MouseButton,
     pub point: DevicePoint,
+    webdriver_id: Option<WebDriverMessageId>,
+}
+
+impl MouseButtonEvent {
+    pub fn new(action: MouseButtonAction, button: MouseButton, point: DevicePoint) -> Self {
+        Self {
+            action,
+            button,
+            point,
+            webdriver_id: None,
+        }
+    }
 }
 
 #[derive(Clone, Copy, Debug, Deserialize, Serialize)]
@@ -102,6 +148,16 @@ pub enum MouseButtonAction {
 #[derive(Clone, Copy, Debug, Deserialize, Serialize)]
 pub struct MouseMoveEvent {
     pub point: DevicePoint,
+    webdriver_id: Option<WebDriverMessageId>,
+}
+
+impl MouseMoveEvent {
+    pub fn new(point: DevicePoint) -> Self {
+        Self {
+            point,
+            webdriver_id: None,
+        }
+    }
 }
 
 /// The type of input represented by a multi-touch event.

components/shared/embedder/webdriver.rs

@@ -24,6 +24,9 @@ use webrender_api::units::DeviceIntSize;
 
 use crate::{MouseButton, MouseButtonAction};
 
+#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
+pub struct WebDriverMessageId(pub usize);
+
 /// Messages to the constellation originating from the WebDriver server.
 #[derive(Debug, Deserialize, Serialize)]
 pub enum WebDriverCommandMsg {
@@ -41,9 +44,23 @@ pub enum WebDriverCommandMsg {
     /// Act as if keys were pressed or release in the browsing context with the given ID.
     KeyboardAction(BrowsingContextId, KeyboardEvent),
     /// Act as if the mouse was clicked in the browsing context with the given ID.
-    MouseButtonAction(WebViewId, MouseButtonAction, MouseButton, f32, f32),
+    MouseButtonAction(
+        WebViewId,
+        MouseButtonAction,
+        MouseButton,
+        f32,
+        f32,
+        WebDriverMessageId,
+        IpcSender<WebDriverCommandResponse>,
+    ),
     /// Act as if the mouse was moved in the browsing context with the given ID.
-    MouseMoveAction(WebViewId, f32, f32),
+    MouseMoveAction(
+        WebViewId,
+        f32,
+        f32,
+        WebDriverMessageId,
+        IpcSender<WebDriverCommandResponse>,
+    ),
     /// Act as if the mouse wheel is scrolled in the browsing context given the given ID.
     WheelScrollAction(WebViewId, f32, f32, f64, f64),
     /// Set the window size.
@@ -188,6 +205,11 @@ pub enum WebDriverFrameId {
     Parent,
 }
 
+#[derive(Debug, Deserialize, Serialize)]
+pub struct WebDriverCommandResponse {
+    pub id: WebDriverMessageId,
+}
+
 #[derive(Debug, Deserialize, Serialize)]
 pub enum WebDriverLoadStatus {
     Complete,