script: Have FetchResponseListener::process_response_eof consume the listener (#40556)

The goal of this change is to prevent having to copy so much data out of
listeners when a fetch completes, which will be particularly important
for off-the-main thread parsing of CSS (see #22478). This change has
pros and cons:

Pros:
- This makes the design of the `FetchResponseListener` a great deal
simpler.
They no longer individually store a dummy `ResourceFetchTiming` that is
   only replaced right before `process_response_eof`.
 - The creation of the `Arc<Mutex<FetchResponseListener>>` in the
   `NetworkListener` is abstracted away from clients and now they just
   pass the `FetchResponseListener` to the fetch methods in the global.

Cons:
 - Now each `FetchResponseListener` must explicitly call `submit_timing`
   instead of having the `NetworkListener` do it. This is arguably a bit
   easier to follow in the code.
 - Since the internal data of the `NetworkListener` is now an
   `Arc<Mutex<Option<FetchResponseListener>>>`, when the fetching code
   needs to share state with the `NetworkListener` it either needs to
   share an `Option` or some sort of internal state. In one case I've
   stored the `Option` and in another case, I've stored a new inner
   shared value.

Testing: This should not change observable behavior and is thus covered
by existing tests.
Fixes: #22550

---------

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/html/htmlimageelement.rs

@@ -24,7 +24,6 @@ use net_traits::image_cache::{
 use net_traits::request::{CorsSettings, Destination, Initiator, RequestId};
 use net_traits::{
     FetchMetadata, FetchResponseMsg, NetworkError, ReferrerPolicy, ResourceFetchTiming,
-    ResourceTimingType,
 };
 use num_traits::ToPrimitive;
 use pixels::{CorsStatus, ImageMetadata, Snapshot};
@@ -233,8 +232,6 @@ struct ImageContext {
     aborted: bool,
     /// The document associated with this request
     doc: Trusted<Document>,
-    /// timing data for this resource
-    resource_timing: ResourceFetchTiming,
     url: ServoUrl,
     element: Trusted<HTMLImageElement>,
 }
@@ -304,26 +301,17 @@ impl FetchResponseListener for ImageContext {
     }
 
     fn process_response_eof(
-        &mut self,
+        self,
         request_id: RequestId,
         response: Result<ResourceFetchTiming, NetworkError>,
     ) {
         self.image_cache.notify_pending_response(
             self.id,
-            FetchResponseMsg::ProcessResponseEOF(request_id, response),
+            FetchResponseMsg::ProcessResponseEOF(request_id, response.clone()),
         );
-    }
-
-    fn resource_timing_mut(&mut self) -> &mut ResourceFetchTiming {
-        &mut self.resource_timing
-    }
-
-    fn resource_timing(&self) -> &ResourceFetchTiming {
-        &self.resource_timing
-    }
-
-    fn submit_resource_timing(&mut self) {
-        network_listener::submit_timing(self, CanGc::note())
+        if let Ok(response) = response {
+            network_listener::submit_timing(&self, &response, CanGc::note());
+        }
     }
 
     fn process_csp_violations(&mut self, _request_id: RequestId, violations: Vec<Violation>) {
@@ -438,7 +426,6 @@ impl HTMLImageElement {
             aborted: false,
             doc: Trusted::new(&document),
             element: Trusted::new(self),
-            resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
             url: img_url.clone(),
         };