Webdriver GoBack and GoForward commands wait for navigation complete (#37950)

After sending `GoBack` or `GoForward` command, webdriver wait for the
navigation complete.
It can be achieved by waiting for
`WebViewDelegate::notify_history_changed`

Testing: 
`tests/wpt/meta/webdriver/tests/classic/back/back.py`
`tests/wpt/meta/webdriver/tests/classic/forward/forward.py`

---------

Signed-off-by: batu_hoang <longvatrong111@gmail.com>
Signed-off-by: Josh Matthews <josh@joshmatthews.net>
Signed-off-by: batu_hoang <hoang.binh.trong@huawei.com>
Co-authored-by: Josh Matthews <josh@joshmatthews.net>

components/shared/constellation/lib.rs

@@ -20,7 +20,7 @@ use base::cross_process_instant::CrossProcessInstant;
 use base::id::{MessagePortId, PipelineId, WebViewId};
 use embedder_traits::{
     CompositorHitTestResult, Cursor, InputEvent, JavaScriptEvaluationId, MediaSessionActionType,
-    Theme, ViewportDetails, WebDriverCommandMsg, WebDriverCommandResponse,
+    Theme, TraversalId, ViewportDetails, WebDriverCommandMsg, WebDriverCommandResponse,
 };
 pub use from_script_message::*;
 use ipc_channel::ipc::IpcSender;
@@ -48,7 +48,7 @@ pub enum EmbedderToConstellationMessage {
     /// Clear the network cache.
     ClearCache,
     /// Request to traverse the joint session history of the provided browsing context.
-    TraverseHistory(WebViewId, TraversalDirection),
+    TraverseHistory(WebViewId, TraversalDirection, TraversalId),
     /// Inform the Constellation that a `WebView`'s [`ViewportDetails`] have changed.
     ChangeViewportDetails(WebViewId, ViewportDetails, WindowSizeType),
     /// Inform the constellation of a theme change.

components/shared/embedder/Cargo.toml

@@ -37,6 +37,7 @@ strum_macros = { workspace = true }
 stylo_traits = { workspace = true }
 stylo = { workspace = true }
 url = { workspace = true }
+uuid = { workspace = true }
 webdriver = { workspace = true }
 webrender_api = { workspace = true }
 servo_geometry = { path = "../../geometry" }

components/shared/embedder/lib.rs

@@ -37,6 +37,7 @@ use strum_macros::IntoStaticStr;
 use style::queries::values::PrefersColorScheme;
 use style_traits::CSSPixel;
 use url::Url;
+use uuid::Uuid;
 use webrender_api::units::{DeviceIntPoint, DeviceIntRect, DeviceIntSize, DevicePixel};
 
 pub use crate::input_events::*;
@@ -318,6 +319,17 @@ pub struct ScreenMetrics {
     pub available_size: DeviceIndependentIntSize,
 }
 
+/// An opaque identifier for a single history traversal operation.
+#[derive(Clone, Deserialize, PartialEq, Serialize)]
+pub struct TraversalId(String);
+
+impl TraversalId {
+    #[allow(clippy::new_without_default)]
+    pub fn new() -> Self {
+        Self(Uuid::new_v4().to_string())
+    }
+}
+
 #[derive(Deserialize, IntoStaticStr, Serialize)]
 pub enum EmbedderMsg {
     /// A status message to be displayed by the browser chrome.
@@ -372,6 +384,8 @@ pub enum EmbedderMsg {
     NewFavicon(WebViewId, ServoUrl),
     /// The history state has changed.
     HistoryChanged(WebViewId, Vec<ServoUrl>, usize),
+    /// A history traversal operation completed.
+    HistoryTraversalComplete(WebViewId, TraversalId),
     /// Get the device independent window rectangle.
     GetWindowRect(WebViewId, IpcSender<DeviceIndependentIntRect>),
     /// Get the device independent screen size and available size.

components/shared/embedder/webdriver.rs

@@ -49,9 +49,9 @@ pub enum WebDriverCommandMsg {
     /// Refresh the top-level browsing context with the given ID.
     Refresh(WebViewId, IpcSender<WebDriverLoadStatus>),
     /// Navigate the webview with the given ID to the previous page in the browsing context's history.
-    GoBack(WebViewId),
+    GoBack(WebViewId, IpcSender<WebDriverLoadStatus>),
     /// Navigate the webview with the given ID to the next page in the browsing context's history.
-    GoForward(WebViewId),
+    GoForward(WebViewId, IpcSender<WebDriverLoadStatus>),
     /// Pass a webdriver command to the script thread of the current pipeline
     /// of a browsing context.
     ScriptCommand(BrowsingContextId, WebDriverScriptCommand),