DevTools: Implement support for showing source_content in Debugger > Source panel (#36774)

This patch adds support for showing source_content in `Debugger >
Source` panel. This works by handling the clients `source` messages in
the source actor. These source actors are already advertised as resource
via the watcher, populating the source list. We also update the
`sources` handler in thread actor for future work in thread debugging.

Note: while this PR also adds support for showing worker script
source_content, worker has been broken (See
https://github.com/servo/servo/issues/37012). I was able to confirm the
`content_type` and `source_content` for worker script in logs.


![image](https://github.com/user-attachments/assets/bd53ea29-003a-4b5e-a3e8-6e280afa4671)

Fixes: part of https://github.com/servo/servo/issues/36027

---------

Signed-off-by: atbrakhi <atbrakhi@igalia.com>

components/devtools/actors/source.rs

@@ -4,10 +4,16 @@
 
 use std::cell::{Ref, RefCell};
 use std::collections::BTreeSet;
+use std::net::TcpStream;
 
 use serde::Serialize;
+use serde_json::{Map, Value};
 use servo_url::ServoUrl;
 
+use crate::StreamId;
+use crate::actor::{Actor, ActorMessageStatus, ActorRegistry};
+use crate::protocol::JsonPacketStream;
+
 #[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd, Serialize)]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct SourceData {
@@ -15,6 +21,7 @@ pub(crate) struct SourceData {
     /// URL of the script, or URL of the page for inline scripts.
     pub url: String,
     pub is_black_boxed: bool,
+    pub source_content: String,
 }
 
 #[derive(Serialize)]
@@ -23,24 +30,38 @@ pub(crate) struct SourcesReply {
     pub sources: Vec<SourceData>,
 }
 
-pub(crate) struct Source {
-    actor_name: String,
-    source_urls: RefCell<BTreeSet<SourceData>>,
+pub(crate) struct SourceManager {
+    pub source_urls: RefCell<BTreeSet<SourceData>>,
 }
 
-impl Source {
-    pub fn new(actor_name: String) -> Self {
+#[derive(Clone, Debug)]
+pub struct SourceActor {
+    pub name: String,
+    pub content: String,
+    pub content_type: String,
+}
+
+#[derive(Serialize)]
+struct SourceContentReply {
+    from: String,
+    #[serde(rename = "contentType")]
+    content_type: String,
+    source: String,
+}
+
+impl SourceManager {
+    pub fn new() -> Self {
         Self {
-            actor_name,
             source_urls: RefCell::new(BTreeSet::default()),
         }
     }
 
-    pub fn add_source(&self, url: ServoUrl) {
+    pub fn add_source(&self, url: ServoUrl, source_content: String, actor_name: String) {
         self.source_urls.borrow_mut().insert(SourceData {
-            actor: self.actor_name.clone(),
+            actor: actor_name,
             url: url.to_string(),
             is_black_boxed: false,
+            source_content,
         });
     }
 
@@ -48,3 +69,51 @@ impl Source {
         self.source_urls.borrow()
     }
 }
+
+impl SourceActor {
+    pub fn new(name: String, content: String, content_type: String) -> SourceActor {
+        SourceActor {
+            name,
+            content,
+            content_type,
+        }
+    }
+
+    pub fn new_source(actors: &mut ActorRegistry, content: String, content_type: String) -> String {
+        let source_actor_name = actors.new_name("source");
+
+        let source_actor = SourceActor::new(source_actor_name.clone(), content, content_type);
+        actors.register(Box::new(source_actor));
+
+        source_actor_name
+    }
+}
+
+impl Actor for SourceActor {
+    fn name(&self) -> String {
+        self.name.clone()
+    }
+
+    fn handle_message(
+        &self,
+        _registry: &ActorRegistry,
+        msg_type: &str,
+        _msg: &Map<String, Value>,
+        stream: &mut TcpStream,
+        _id: StreamId,
+    ) -> Result<ActorMessageStatus, ()> {
+        Ok(match msg_type {
+            // Client has requested contents of the source.
+            "source" => {
+                let reply = SourceContentReply {
+                    from: self.name(),
+                    content_type: self.content_type.clone(),
+                    source: self.content.clone(),
+                };
+                let _ = stream.write_json_packet(&reply);
+                ActorMessageStatus::Processed
+            },
+            _ => ActorMessageStatus::Ignored,
+        })
+    }
+}