Ability to create new TopLevelBrowsingContext

components/compositing/compositor.rs

@@ -818,6 +818,13 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 self.webrender.set_profiler_enabled(!profiler_enabled);
                 self.webrender_api.generate_frame(self.webrender_document, None);
             }
+
+            WindowEvent::NewBrowser(url, response_chan) => {
+                let msg = ConstellationMsg::NewBrowser(url, response_chan);
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!("Sending NewBrowser message to constellation failed ({}).", e);
+                }
+            }
         }
     }
 

components/compositing/windowing.rs

@@ -71,6 +71,8 @@ pub enum WindowEvent {
     /// Toggles the Web renderer profiler on and off
     ToggleWebRenderProfiler,
     Reload(TopLevelBrowsingContextId),
+    /// Create a new top level browsing context
+    NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
 }
 
 impl Debug for WindowEvent {
@@ -93,6 +95,7 @@ impl Debug for WindowEvent {
             WindowEvent::Quit => write!(f, "Quit"),
             WindowEvent::ToggleWebRenderProfiler => write!(f, "ToggleWebRenderProfiler"),
             WindowEvent::Reload(..) => write!(f, "Reload"),
+            WindowEvent::NewBrowser(..) => write!(f, "NewBrowser"),
         }
     }
 }

components/constellation/constellation.rs

@@ -955,10 +955,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                     println!("sent response");
                 }
             }
-            // This should only be called once per constellation, and only by the browser
+            // Create a new top level browsing context. Will use response_chan to return
-            FromCompositorMsg::InitLoadUrl(url) => {
+            // the browsing context id.
+            FromCompositorMsg::NewBrowser(url, response_chan) => {
                 debug!("constellation got init load URL message");
-                self.handle_init_load(url);
+                self.handle_new_top_level_browsing_context(url, response_chan);
             }
             // Handle a forward or back request
             FromCompositorMsg::TraverseHistory(top_level_browsing_context_id, direction) => {
@@ -1473,14 +1474,19 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         }
     }
 
-    fn handle_init_load(&mut self, url: ServoUrl) {
+    fn handle_new_top_level_browsing_context(&mut self, url: ServoUrl, reply: IpcSender<TopLevelBrowsingContextId>) {
         let window_size = self.window_size.initial_viewport;
         let pipeline_id = PipelineId::new();
         let top_level_browsing_context_id = TopLevelBrowsingContextId::new();
+        if let Err(e) = reply.send(top_level_browsing_context_id) {
+            warn!("Failed to send newly created top level browsing context ({}).", e);
+        }
         let browsing_context_id = BrowsingContextId::from(top_level_browsing_context_id);
         let load_data = LoadData::new(url.clone(), None, None, None);
         let sandbox = IFrameSandboxState::IFrameUnsandboxed;
+        if self.focus_pipeline_id.is_none() {
             self.focus_pipeline_id = Some(pipeline_id);
+        }
         self.new_pipeline(pipeline_id,
                           browsing_context_id,
                           top_level_browsing_context_id,

components/script_traits/lib.rs

@@ -740,8 +740,6 @@ pub enum ConstellationMsg {
     /// Request that the constellation send the current focused top-level browsing context id,
     /// over a provided channel.
     GetFocusTopLevelBrowsingContext(IpcSender<Option<TopLevelBrowsingContextId>>),
-    /// Request to load the initial page.
-    InitLoadUrl(ServoUrl),
     /// Query the constellation to see if the current compositor output is stable
     IsReadyToSaveImage(HashMap<PipelineId, Epoch>),
     /// Inform the constellation of a key event.
@@ -764,6 +762,8 @@ pub enum ConstellationMsg {
     SetWebVRThread(IpcSender<WebVRMsg>),
     /// Dispatch WebVR events to the subscribed script threads.
     WebVREvents(Vec<PipelineId>, Vec<WebVREvent>),
+    /// Create a new top level browsing context.
+    NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
 }
 
 /// Resources required by workerglobalscopes

components/servo/lib.rs

@@ -92,7 +92,6 @@ use script_traits::{ConstellationMsg, SWManagerSenders, ScriptMsg};
 use servo_config::opts;
 use servo_config::prefs::PREFS;
 use servo_config::resource_files::resources_dir_path;
-use servo_url::ServoUrl;
 use std::borrow::Cow;
 use std::cmp::max;
 use std::path::PathBuf;
@@ -104,6 +103,7 @@ use webvr::{WebVRThread, WebVRCompositorHandler};
 pub use gleam::gl;
 pub use servo_config as config;
 pub use servo_url as url;
+pub use msg::constellation_msg::TopLevelBrowsingContextId as BrowserId;
 
 /// The in-process interface to Servo.
 ///
@@ -202,7 +202,6 @@ impl<Window> Browser<Window> where Window: WindowMethods + 'static {
         // as the navigation context.
         let (constellation_chan, sw_senders) = create_constellation(opts.user_agent.clone(),
                                                                     opts.config_dir.clone(),
-                                                                    target_url,
                                                                     compositor_proxy.clone_compositor_proxy(),
                                                                     time_profiler_chan.clone(),
                                                                     mem_profiler_chan.clone(),
@@ -280,7 +279,6 @@ fn create_compositor_channel(event_loop_waker: Box<compositor_thread::EventLoopW
 
 fn create_constellation(user_agent: Cow<'static, str>,
                         config_dir: Option<PathBuf>,
-                        url: ServoUrl,
                         compositor_proxy: CompositorProxy,
                         time_profiler_chan: time::ProfilerChan,
                         mem_profiler_chan: mem::ProfilerChan,
@@ -332,8 +330,6 @@ fn create_constellation(user_agent: Cow<'static, str>,
         constellation_chan.send(ConstellationMsg::SetWebVRThread(webvr_thread)).unwrap();
     }
 
-    constellation_chan.send(ConstellationMsg::InitLoadUrl(url)).unwrap();
-
     // channels to communicate with Service Worker Manager
     let sw_senders = SWManagerSenders {
         swmanager_sender: from_swmanager_sender,