Devtools device description: improve how Servo is advertised in Firefox's about:debugging (fixes #27528) (#32227)

* Devtools device description: fix the case of the 'platformversion' property

* Devtools device description: expose the properties Firefox expects for the display name and version of the server

When connecting to Servo from Firefox (about:debugging), it will display "Servo (71.0)" instead of "{$name} (${version})".

* Devtools device description: update versions to match those in the UA string

* Devtools device description: expose a property (appbuildid) Firefox expects to compare versions for compatibility (_compareVersionCompatibility function)

* Devtools device description: advertise a current platform version to remove the incompatibility warning in Firefox's about:debugging

* Devtools preference actor: fix retrieving the actual preference by its key

* Devtools preference actor: translate Firefox preference names onto the corresponding Servo preference names

* Devtools device description: downgrade the platform version to prevent a confusing warning in about:debugging if the build ID is newer than that of Firefox (likely)

* Devtools device description: add comments

* Devtools device description: use CARGO_PKG_VERSION for the user-visible version number

1 files changed, 17 insertions, 2 deletions

diff --git a/components/devtools/actors/device.rs b/components/devtools/actors/device.rs
index ed4c7993c9c..3fb5eb9a0a7 100644
--- a/components/devtools/actors/device.rs
+++ b/components/devtools/actors/device.rs
@@ -17,12 +17,24 @@ struct GetDescriptionReply {
     value: SystemInfo,
 }
 
+// This is only a minimal subset of the properties exposed/expected by Firefox
+// (see https://searchfox.org/mozilla-central/source/devtools/shared/system.js#45)
 #[derive(Serialize)]
 struct SystemInfo {
     apptype: String,
-    platformVersion: String,
+    // Display version
+    version: String,
+    // Build ID (timestamp with format YYYYMMDDhhmmss), used for compatibility checks
+    // (see https://searchfox.org/mozilla-central/source/devtools/client/shared/remote-debugging/version-checker.js#82)
+    appbuildid: String,
+    // Firefox major.minor version number, use for compatibility checks
+    platformversion: String,
+    // Display name
+    brandName: String,
 }
 
+include!(concat!(env!("OUT_DIR"), "/build_id.rs"));
+
 pub struct DeviceActor {
     pub name: String,
 }
@@ -45,7 +57,10 @@ impl Actor for DeviceActor {
                     from: self.name(),
                     value: SystemInfo {
                         apptype: "servo".to_string(),
-                        platformVersion: "71.0".to_string(),
+                        version: env!("CARGO_PKG_VERSION").to_string(),
+                        appbuildid: BUILD_ID.to_string(),
+                        platformversion: "124.0".to_string(),
+                        brandName: "Servo".to_string(),
                     },
                 };
                 let _ = stream.write_json_packet(&msg);