Introduce embedder MediaSessionEvent and move active session to Servo

components/constellation/constellation.rs

@@ -1778,9 +1778,6 @@ where
                     new_value,
                 );
             },
-            FromScriptMsg::MediaSessionEventMsg(browser_id, event) => {
-                // TODO
-            },
         }
     }
 

components/embedder_traits/lib.rs

@@ -162,9 +162,9 @@ pub enum EmbedderMsg {
     Shutdown,
     /// Report a complete sampled profile
     ReportProfile(Vec<u8>),
-    /// Sent when a media session is activated or deactivated.
-    /// There can only be a single active media session.
-    MediaSession(bool),
+    /// Notifies the embedder about media session events
+    /// (i.e. when there is metadata for the active media session, playback state changes...).
+    MediaSessionEvent(MediaSessionEvent),
 }
 
 impl Debug for EmbedderMsg {
@@ -197,7 +197,7 @@ impl Debug for EmbedderMsg {
             EmbedderMsg::AllowOpeningBrowser(..) => write!(f, "AllowOpeningBrowser"),
             EmbedderMsg::BrowserCreated(..) => write!(f, "BrowserCreated"),
             EmbedderMsg::ReportProfile(..) => write!(f, "ReportProfile"),
-            EmbedderMsg::MediaSession(..) => write!(f, "MediaSession"),
+            EmbedderMsg::MediaSessionEvent(..) => write!(f, "MediaSessionEvent"),
         }
     }
 }
@@ -206,3 +206,34 @@ impl Debug for EmbedderMsg {
 /// the `String` content is expected to be extension (e.g, "doc", without the prefixing ".")
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub struct FilterPattern(pub String);
+
+/// https://w3c.github.io/mediasession/#mediametadata
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct MediaMetadata {
+    /// Title
+    pub title: String,
+    /// Artist
+    pub artist: Option<String>,
+    /// Album
+    pub album: Option<String>,
+}
+
+/// https://w3c.github.io/mediasession/#enumdef-mediasessionplaybackstate
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub enum MediaSessionPlaybackState {
+    /// The browsing context does not specify whether it’s playing or paused.
+    None_,
+    /// The browsing context has paused media and it can be resumed.
+    Playing,
+    /// The browsing context is currently playing media and it can be paused.
+    Paused,
+}
+
+/// Type of events sent from script to the embedder about the media session.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub enum MediaSessionEvent {
+    /// Indicates that the media metadata is available.
+    SetMetadata(MediaMetadata),
+    /// Indicates that the playback state has changed.
+    PlaybackStateChange(MediaSessionPlaybackState),
+}

components/script/dom/htmlmediaelement.rs

@@ -67,6 +67,7 @@ use crate::script_thread::ScriptThread;
 use crate::task_source::TaskSource;
 use dom_struct::dom_struct;
 use embedder_traits::resources::{self, Resource as EmbedderResource};
+use embedder_traits::{MediaMetadata, MediaSessionEvent};
 use euclid::default::Size2D;
 use headers::{ContentLength, ContentRange, HeaderMapExt};
 use html5ever::{LocalName, Prefix};
@@ -80,7 +81,6 @@ use net_traits::request::{Destination, Referrer};
 use net_traits::{CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, Metadata};
 use net_traits::{NetworkError, ResourceFetchTiming, ResourceTimingType};
 use script_layout_interface::HTMLMediaData;
-use script_traits::MediaSessionEvent;
 use servo_config::pref;
 use servo_media::player::audio::AudioRenderer;
 use servo_media::player::video::{VideoFrame, VideoFrameRenderer};
@@ -1727,6 +1727,14 @@ impl HTMLMediaElement {
                 if self.Controls() {
                     self.render_controls();
                 }
+
+                // Send a media session event with the obtained metadata.
+                self.send_media_session_event(MediaSessionEvent::SetMetadata(MediaMetadata {
+                    // TODO(ferjm) set url if no title.
+                    title: metadata.title.clone().unwrap_or("".to_string()),
+                    artist: None,
+                    album: None,
+                }));
             },
             PlayerEvent::NeedData => {
                 // The player needs more data.

components/script/dom/mediasession.rs

@@ -16,8 +16,9 @@ use crate::dom::mediametadata::MediaMetadata;
 use crate::dom::window::Window;
 use crate::script_thread::ScriptThread;
 use dom_struct::dom_struct;
+use embedder_traits::{EmbedderMsg, MediaSessionEvent};
 use msg::constellation_msg::TopLevelBrowsingContextId;
-use script_traits::{MediaSessionActionType, MediaSessionEvent, ScriptMsg};
+use script_traits::MediaSessionActionType;
 use std::collections::HashMap;
 use std::rc::Rc;
 
@@ -71,14 +72,8 @@ impl MediaSession {
 
     pub fn send_event(&self, event: MediaSessionEvent) {
         let global = self.global();
-        let browser_id = global
-            .as_window()
-            .window_proxy()
-            .top_level_browsing_context_id();
-        let _ = global
-            .script_to_constellation_chan()
-            .send(ScriptMsg::MediaSessionEventMsg(browser_id, event))
-            .unwrap();
+        let window = global.as_window();
+        window.send_to_embedder(EmbedderMsg::MediaSessionEvent(event));
     }
 }
 

components/script_traits/lib.rs

@@ -1087,34 +1087,3 @@ pub enum MediaSessionActionType {
     /// The action intent is to move the playback time to a specific time.
     SeekTo,
 }
-
-/// https://w3c.github.io/mediasession/#mediametadata
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub struct MediaMetadata {
-    /// Title
-    pub title: String,
-    /// Artist
-    pub artist: Option<String>,
-    /// Album
-    pub album: Option<String>,
-}
-
-/// https://w3c.github.io/mediasession/#enumdef-mediasessionplaybackstate
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub enum MediaSessionPlaybackState {
-    /// The browsing context does not specify whether it’s playing or paused.
-    None_,
-    /// The browsing context has paused media and it can be resumed.
-    Playing,
-    /// The browsing context is currently playing media and it can be paused.
-    Paused,
-}
-
-/// Type of events sent from script to the constellation about the media session.
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub enum MediaSessionEvent {
-    /// Indicates that the media metadata is available.
-    SetMetadata(MediaMetadata),
-    /// Indicates that the playback state has changed.
-    PlaybackStateChange(MediaSessionPlaybackState),
-}

components/script_traits/script_msg.rs

@@ -255,9 +255,6 @@ pub enum ScriptMsg {
     GetScreenSize(IpcSender<DeviceIntSize>),
     /// Get the available screen size (pixel)
     GetScreenAvailSize(IpcSender<DeviceIntSize>),
-    /// Notifies the constellation about media session events
-    /// (i.e. when there is metadata for the active media session, playback state changes...).
-    MediaSessionEventMsg(TopLevelBrowsingContextId, MediaSessionEvent),
 }
 
 impl fmt::Debug for ScriptMsg {
@@ -309,7 +306,6 @@ impl fmt::Debug for ScriptMsg {
             GetClientWindow(..) => "GetClientWindow",
             GetScreenSize(..) => "GetScreenSize",
             GetScreenAvailSize(..) => "GetScreenAvailSize",
-            MediaSessionEventMsg(..) => "MediaSessionEventMsg",
         };
         write!(formatter, "ScriptMsg::{}", variant)
     }

components/servo/lib.rs

@@ -83,6 +83,7 @@ use constellation::{Constellation, InitialConstellationState, UnprivilegedPipeli
 use constellation::{FromCompositorLogger, FromScriptLogger};
 use crossbeam_channel::{unbounded, Sender};
 use embedder_traits::{EmbedderMsg, EmbedderProxy, EmbedderReceiver, EventLoopWaker};
+use embedder_traits::{MediaSessionEvent, MediaSessionPlaybackState};
 use env_logger::Builder as EnvLoggerBuilder;
 use euclid::{Scale, Size2D};
 #[cfg(all(
@@ -270,6 +271,9 @@ pub struct Servo<Window: WindowMethods + 'static + ?Sized> {
     embedder_receiver: EmbedderReceiver,
     embedder_events: Vec<(Option<BrowserId>, EmbedderMsg)>,
     profiler_enabled: bool,
+    webgl_thread_data: Option<Rc<WebGLMainThread>>,
+    /// Browser ID of the active media session, if any.
+    active_media_session: Option<BrowserId>,
 }
 
 #[derive(Clone)]
@@ -555,6 +559,8 @@ where
             embedder_receiver: embedder_receiver,
             embedder_events: Vec::new(),
             profiler_enabled: false,
+            webgl_thread_data,
+            active_media_session: None,
         }
     }
 
@@ -744,6 +750,31 @@ where
                     self.embedder_events.push(event);
                 },
 
+                (EmbedderMsg::MediaSessionEvent(event), ShutdownState::NotShuttingDown) => {
+                    // Unlikely at this point, but we may receive events coming from
+                    // different media sessions, so we set the active media session based
+                    // on Playing events.
+                    // The last media session claiming to be in playing state is set to
+                    // the active media session.
+                    // Events coming from inactive media sessions are discarded.
+                    if self.active_media_session.is_some() {
+                        match event {
+                            MediaSessionEvent::PlaybackStateChange(ref state) => {
+                                match state {
+                                    MediaSessionPlaybackState::Playing => (),
+                                    _ => return,
+                                };
+                            },
+                            _ => (),
+                        };
+                    }
+                    self.active_media_session = top_level_browsing_context;
+                    self.embedder_events.push((
+                        top_level_browsing_context,
+                        EmbedderMsg::MediaSessionEvent(event),
+                    ));
+                },
+
                 (msg, ShutdownState::NotShuttingDown) => {
                     self.embedder_events.push((top_level_browsing_context, msg));
                 },