[WebDriver] Add synchronization for key action (#37403)

Implement action synchronization for key event. Previously only done for
pointer https://github.com/servo/servo/pull/36932 and wheel
https://github.com/servo/servo/pull/37260.

---------

Signed-off-by: PotatoCP <kenzieradityatirtarahardja18@gmail.com>

components/webdriver_server/actions.rs

@@ -157,7 +157,7 @@ impl Handler {
             // Step 1.4. Wait for
             // The user agent event loop has spun enough times to process the DOM events
             // generated by the last invocation of the dispatch tick actions steps.
-            self.wait_for_user_agent_handling_complete(tick_actions)?;
+            self.wait_for_user_agent_handling_complete()?;
             // At least tick duration milliseconds have passed.
             let elapsed = now.elapsed();
             if elapsed.as_millis() < tick_duration as u128 {
@@ -171,29 +171,13 @@ impl Handler {
         Ok(())
     }
 
-    fn wait_for_user_agent_handling_complete(
-        &self,
-        tick_actions: &TickActions,
-    ) -> Result<(), ErrorStatus> {
-        // TODO: Add matches! for key actions
-        // after implmenting webdriver id for key events.
-        let count_non_null_actions_in_tick = tick_actions
-            .iter()
-            .filter(|(_, action)| {
-                matches!(
-                    action,
-                    ActionItem::Pointer(PointerActionItem::Pointer(_)) |
-                        ActionItem::Wheel(WheelActionItem::Wheel(_))
-                )
-            })
-            .count();
-
+    fn wait_for_user_agent_handling_complete(&self) -> Result<(), ErrorStatus> {
         // To ensure we wait for all events to be processed, only the last event
         // in each tick action step holds the message id.
         // Whenever a new event is generated, the message id is passed to it.
         //
-        // Wait for count_non_null_actions_in_tick number of responses
-        for _ in 0..count_non_null_actions_in_tick {
+        // Wait for num_pending_actions number of responses
+        for _ in 0..self.num_pending_actions.get() {
             match self.constellation_receiver.recv() {
                 Ok(response) => {
                     let current_waiting_id = self
@@ -213,6 +197,8 @@ impl Handler {
             };
         }
 
+        self.num_pending_actions.set(0);
+
         Ok(())
     }
 
@@ -320,9 +306,13 @@ impl Handler {
         let keyboard_event = key_input_state.dispatch_keydown(raw_key);
 
         // Step 12
+        self.increment_num_pending_actions();
+        let msg_id = self.current_action_id.get();
         let cmd_msg = WebDriverCommandMsg::KeyboardAction(
             self.session().unwrap().browsing_context_id,
             keyboard_event,
+            msg_id,
+            self.constellation_sender.clone(),
         );
         self.constellation_chan
             .send(EmbedderToConstellationMessage::WebDriverCommand(cmd_msg))
@@ -342,9 +332,13 @@ impl Handler {
 
         if let Some(keyboard_event) = key_input_state.dispatch_keyup(raw_key) {
             // Step 12
+            self.increment_num_pending_actions();
+            let msg_id = self.current_action_id.get();
             let cmd_msg = WebDriverCommandMsg::KeyboardAction(
                 self.session().unwrap().browsing_context_id,
                 keyboard_event,
+                msg_id,
+                self.constellation_sender.clone(),
             );
             self.constellation_chan
                 .send(EmbedderToConstellationMessage::WebDriverCommand(cmd_msg))
@@ -367,6 +361,7 @@ impl Handler {
         }
         pointer_input_state.pressed.insert(action.button);
 
+        self.increment_num_pending_actions();
         let msg_id = self.current_action_id.get();
         let cmd_msg = WebDriverCommandMsg::MouseButtonAction(
             session.webview_id,
@@ -397,6 +392,7 @@ impl Handler {
         }
         pointer_input_state.pressed.remove(&action.button);
 
+        self.increment_num_pending_actions();
         let msg_id = self.current_action_id.get();
         let cmd_msg = WebDriverCommandMsg::MouseButtonAction(
             session.webview_id,
@@ -523,6 +519,7 @@ impl Handler {
             if x != current_x || y != current_y || last {
                 // Step 7.2
                 let msg_id = if last {
+                    self.increment_num_pending_actions();
                     self.current_action_id.get()
                 } else {
                     None
@@ -660,6 +657,7 @@ impl Handler {
         if delta_x != 0 || delta_y != 0 || last {
             // Perform implementation-specific action dispatch steps
             let msg_id = if last {
+                self.increment_num_pending_actions();
                 self.current_action_id.get()
             } else {
                 None

components/webdriver_server/lib.rs

@@ -227,6 +227,9 @@ struct Handler {
     current_action_id: Cell<Option<WebDriverMessageId>>,
 
     resize_timeout: u32,
+
+    /// Number of pending actions of which WebDriver is waiting for responses.
+    num_pending_actions: Cell<u32>,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -459,9 +462,16 @@ impl Handler {
             id_generator: WebDriverMessageIdGenerator::new(),
             current_action_id: Cell::new(None),
             resize_timeout: 500,
+            num_pending_actions: Cell::new(0),
         }
     }
 
+    fn increment_num_pending_actions(&self) {
+        // Increase the num_pending_actions by one every time we dispatch non null actions.
+        self.num_pending_actions
+            .set(self.num_pending_actions.get() + 1);
+    }
+
     fn focus_webview_id(&self) -> WebDriverResult<WebViewId> {
         debug!("Getting focused context.");
         let (sender, receiver) = ipc::channel().unwrap();