add CompositorMsg::LoadStart, implement cef_load_handler::on_loading_state_change()

only adds the loading:true callback this time...

components/compositing/compositor.rs

@@ -384,6 +384,10 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 self.scroll_fragment_to_point(pipeline_id, layer_id, point);
             }
 
+            (Msg::LoadStart(back, forward), ShutdownState::NotShuttingDown) => {
+                self.window.load_start(back, forward);
+            }
+
             (Msg::LoadComplete, ShutdownState::NotShuttingDown) => {
                 self.got_load_complete_message = true;
 

components/compositing/compositor_task.rs

@@ -160,6 +160,8 @@ pub enum Msg {
     ChangeRunningAnimationsState(PipelineId, AnimationState),
     /// Replaces the current frame tree, typically called during main frame navigation.
     SetFrameTree(SendableFrameTree, Sender<()>, ConstellationChan),
+    /// The load of a page has begun: (can go back, can go forward).
+    LoadStart(bool, bool),
     /// The load of a page has completed.
     LoadComplete,
     /// Indicates that the scrolling timeout with the given starting timestamp has happened and a
@@ -195,6 +197,7 @@ impl Debug for Msg {
             Msg::ChangePageUrl(..) => write!(f, "ChangePageUrl"),
             Msg::SetFrameTree(..) => write!(f, "SetFrameTree"),
             Msg::LoadComplete => write!(f, "LoadComplete"),
+            Msg::LoadStart(..) => write!(f, "LoadStart"),
             Msg::ScrollTimeout(..) => write!(f, "ScrollTimeout"),
             Msg::RecompositeAfterScroll => write!(f, "RecompositeAfterScroll"),
             Msg::KeyEvent(..) => write!(f, "KeyEvent"),

components/compositing/constellation.rs

@@ -520,6 +520,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
         let window_rect = Rect(Point2D::zero(), self.window_size.visible_viewport);
         let root_pipeline_id =
             self.new_pipeline(None, Some(window_rect), None, LoadData::new(url.clone()));
+        self.handle_load_start_msg(&root_pipeline_id);
         self.push_pending_frame(root_pipeline_id, None);
         self.compositor_proxy.send(CompositorMsg::ChangePageUrl(root_pipeline_id, url));
     }
@@ -630,6 +631,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
         // requested change so it can update its internal state.
         match self.pipeline(source_id).parent_info {
             Some((parent_pipeline_id, subpage_id)) => {
+                self.handle_load_start_msg(&source_id);
                 // Message the constellation to find the script task for this iframe
                 // and issue an iframe load through there.
                 let parent_pipeline = self.pipeline(parent_pipeline_id);
@@ -647,6 +649,7 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
                     }
                 }
 
+                self.handle_load_start_msg(&source_id);
                 // Being here means either there are no pending frames, or none of the pending
                 // changes would be overridden by changing the subframe associated with source_id.
 
@@ -662,6 +665,22 @@ impl<LTF: LayoutTaskFactory, STF: ScriptTaskFactory> Constellation<LTF, STF> {
         }
     }
 
+    fn handle_load_start_msg(&mut self, pipeline_id: &PipelineId) {
+        let mut back = false;
+        let mut forward = false;
+        let frameid = self.pipeline_to_frame_map.get(pipeline_id);
+        match frameid {
+            Some(frame_id) => {
+                forward = if !self.frame(*frame_id).next.is_empty() { true }
+                          else { false };
+                back = if !self.frame(*frame_id).prev.is_empty() { true }
+                       else { false };
+            },
+            None => {}
+        };
+        self.compositor_proxy.send(CompositorMsg::LoadStart(back, forward));
+    }
+
     fn handle_load_complete_msg(&mut self) {
         self.compositor_proxy.send(CompositorMsg::LoadComplete);
         if let Some(ref reply_chan) = self.webdriver.load_channel {

components/compositing/headless.rs

@@ -97,6 +97,7 @@ impl CompositorEventListener for NullCompositor {
             Msg::AssignPaintedBuffers(..) |
             Msg::ChangeRunningAnimationsState(..) |
             Msg::ScrollFragmentPoint(..) |
+            Msg::LoadStart(..) |
             Msg::LoadComplete |
             Msg::ScrollTimeout(..) |
             Msg::RecompositeAfterScroll |

components/compositing/windowing.rs

@@ -103,6 +103,8 @@ pub trait WindowMethods {
     fn set_page_title(&self, title: Option<String>);
     /// Sets the load data for the current page.
     fn set_page_url(&self, url: Url);
+    /// Called when the browser has started loading a frame.
+    fn load_start(&self, back: bool, forward: bool);
     /// Called when the browser is done loading a frame.
     fn load_end(&self);
 

ports/cef/window.rs

@@ -315,6 +315,22 @@ impl WindowMethods for Window {
         }
     }
 
+    fn load_start(&self, back: bool, forward: bool) {
+        // FIXME(pcwalton): The status code 200 is a lie.
+        let browser = self.cef_browser.borrow();
+        let browser = match *browser {
+            None => return,
+            Some(ref browser) => browser,
+        };
+        if check_ptr_exist!(browser.get_host().get_client(), get_load_handler) &&
+           check_ptr_exist!(browser.get_host().get_client().get_load_handler(), on_loading_state_change) {
+            browser.get_host()
+                   .get_client()
+                   .get_load_handler()
+                   .on_loading_state_change((*browser).clone(), 1i32, back as i32, forward as i32);
+        }
+    }
+
     fn load_end(&self) {
         // FIXME(pcwalton): The status code 200 is a lie.
         let browser = self.cef_browser.borrow();

ports/glutin/window.rs

@@ -505,6 +505,9 @@ impl WindowMethods for Window {
     fn set_page_url(&self, _: Url) {
     }
 
+    fn load_start(&self, _: bool, _: bool) {
+    }
+
     fn load_end(&self) {
     }
 

ports/gonk/src/window.rs

@@ -802,6 +802,9 @@ impl WindowMethods for Window {
     fn set_page_url(&self, _: Url) {
     }
 
+    fn load_start(&self, _: bool, _: bool) {
+    }
+
     fn load_end(&self) {
     }