Auto merge of #23990 - tomasdivito:add-secure-connection-start, r=jdm

Add secure connection start

Implementing `secure_connection_start` as well as we can, this is related to #21268

We are setting the value as well as we can since we don't have a way to know if we are currently using a secure transport or where the handshake before the connection is done as the spec says on the step 15 [https://w3c.github.io/resource-timing/#sec-process](https://w3c.github.io/resource-timing/#sec-process)

Regarding the Timing Allow Check, that's being done on another PR by another person which will take care of setting the rest of the values on `PerformaceResourceTiming` to Zero and prevent them to set them any other way.

I'm currently setting the `secure_connection_time` using `precise_time_ms()` as the `connection_start` and `connection_end` are set that way... but other attributes inside `PerformanceResourceTiming` are set using `precise_time

Another thing, the issue talks about setting `redirect_start` but I'm not really sure if it's related, if so I can look up into that too... I might have just read and thought it was all about secure connection start.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #21268

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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components/net/http_loader.rs

@@ -424,6 +424,17 @@ fn obtain_response(
         )
         .body(request_body.clone().into());
 
+    // TODO: We currently don't know when the handhhake before the connection is done
+    // so our best bet would be to set `secure_connection_start` here when we are currently
+    // fetching on a HTTPS url.
+    if url.scheme() == "https" {
+        context
+            .timing
+            .lock()
+            .unwrap()
+            .set_attribute(ResourceAttribute::SecureConnectionStart);
+    }
+
     let mut request = match request {
         Ok(request) => request,
         Err(e) => return Box::new(future::result(Err(NetworkError::from_http_error(&e)))),