Auto merge of #18181 - paulrouget:close_browser, r=cbrewster

Make it possible to close a browsing context from the embedder

<!-- Please describe your changes on the following line: -->

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #18006 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/18181)
<!-- Reviewable:end -->

components/compositing/compositor.rs

@@ -828,6 +828,13 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 }
             }
 
+            WindowEvent::CloseBrowser(ctx) => {
+                let msg = ConstellationMsg::CloseBrowser(ctx);
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!("Sending CloseBrowser message to constellation failed ({}).", e);
+                }
+            }
+
             WindowEvent::SelectBrowser(ctx) => {
                 let msg = ConstellationMsg::SelectBrowser(ctx);
                 if let Err(e) = self.constellation_chan.send(msg) {

components/compositing/windowing.rs

@@ -79,6 +79,8 @@ pub enum WindowEvent {
     Reload(TopLevelBrowsingContextId),
     /// Create a new top level browsing context
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
+    /// Close a top level browsing context
+    CloseBrowser(TopLevelBrowsingContextId),
     /// Make a top level browsing context visible, hiding the previous
     /// visible one.
     SelectBrowser(TopLevelBrowsingContextId),
@@ -106,6 +108,7 @@ impl Debug for WindowEvent {
             WindowEvent::Quit => write!(f, "Quit"),
             WindowEvent::Reload(..) => write!(f, "Reload"),
             WindowEvent::NewBrowser(..) => write!(f, "NewBrowser"),
+            WindowEvent::CloseBrowser(..) => write!(f, "CloseBrowser"),
             WindowEvent::SelectBrowser(..) => write!(f, "SelectBrowser"),
             WindowEvent::ToggleWebRenderDebug(..) => write!(f, "ToggleWebRenderDebug"),
         }

components/constellation/constellation.rs

@@ -974,9 +974,14 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             // Create a new top level browsing context. Will use response_chan to return
             // the browsing context id.
             FromCompositorMsg::NewBrowser(url, response_chan) => {
-                debug!("constellation got init load URL message");
+                debug!("constellation got NewBrowser message");
                 self.handle_new_top_level_browsing_context(url, response_chan);
             }
+            // Close a top level browsing context.
+            FromCompositorMsg::CloseBrowser(top_level_browsing_context_id) => {
+                debug!("constellation got CloseBrowser message");
+                self.handle_close_top_level_browsing_context(top_level_browsing_context_id);
+            }
             // Send frame tree to WebRender. Make it visible.
             FromCompositorMsg::SelectBrowser(top_level_browsing_context_id) => {
                 self.send_frame_tree(top_level_browsing_context_id);
@@ -1544,6 +1549,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         });
     }
 
+    fn handle_close_top_level_browsing_context(&mut self, top_level_browsing_context_id: TopLevelBrowsingContextId) {
+        let browsing_context_id = BrowsingContextId::from(top_level_browsing_context_id);
+        self.close_browsing_context(browsing_context_id, ExitPipelineMode::Normal);
+    }
+
     fn handle_iframe_size_msg(&mut self,
                               iframe_sizes: Vec<(BrowsingContextId, TypedSize2D<f32, CSSPixel>)>) {
         for (browsing_context_id, size) in iframe_sizes {

components/script_traits/lib.rs

@@ -767,6 +767,8 @@ pub enum ConstellationMsg {
     WebVREvents(Vec<PipelineId>, Vec<WebVREvent>),
     /// Create a new top level browsing context.
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
+    /// Close a top level browsing context.
+    CloseBrowser(TopLevelBrowsingContextId),
     /// Make browser visible.
     SelectBrowser(TopLevelBrowsingContextId),
 }