Auto merge of #24499 - ferjm:media.session.api, r=Manishearth

Media Session API

- [X] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #24172
- [x] There are tests for these changes

This PR introduces all the pieces required to prove an end to end media session flow with Android as a test platform.

1 files changed, 5 insertions, 1 deletions

diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index a12101380c9..1eccc794398 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -16,7 +16,7 @@ use crate::WorkerGlobalScopeInit;
 use crate::WorkerScriptLoadOrigin;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
-use embedder_traits::EmbedderMsg;
+use embedder_traits::{EmbedderMsg, MediaSessionEvent};
 use euclid::default::Size2D as UntypedSize2D;
 use euclid::Size2D;
 use gfx_traits::Epoch;
@@ -254,6 +254,9 @@ 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...).
+    MediaSessionEvent(PipelineId, MediaSessionEvent),
 }
 
 impl fmt::Debug for ScriptMsg {
@@ -305,6 +308,7 @@ impl fmt::Debug for ScriptMsg {
             GetClientWindow(..) => "GetClientWindow",
             GetScreenSize(..) => "GetScreenSize",
             GetScreenAvailSize(..) => "GetScreenAvailSize",
+            MediaSessionEvent(..) => "MediaSessionEvent",
         };
         write!(formatter, "ScriptMsg::{}", variant)
     }