network: populate response headers size (#875)

Note: In the absence of WPT tests that verify this field, it may be
slightly off by a few bytes.

Bug: #765

Author: Thiago Perrotta

src/bidiMapper/domains/network/networkRequest.ts

@@ -292,6 +292,10 @@ export class NetworkRequest {
       this.#responseReceivedExtraInfoEvent = undefined;
     }
 
+    const headers = NetworkRequest.#getHeaders(
+      this.#responseReceivedEvent.response.headers
+    );
+
     return {
       method: Network.EventNames.ResponseCompletedEvent,
       params: {
@@ -307,13 +311,10 @@ export class NetworkRequest {
             this.#responseReceivedEvent.response.fromDiskCache ||
             this.#responseReceivedEvent.response.fromPrefetchCache ||
             this.#servedFromCache,
-          headers: NetworkRequest.#getHeaders(
-            this.#responseReceivedEvent.response.headers
-          ),
+          headers,
           mimeType: this.#responseReceivedEvent.response.mimeType,
           bytesReceived: this.#responseReceivedEvent.response.encodedDataLength,
-          headersSize:
-            this.#responseReceivedExtraInfoEvent?.headersText?.length ?? 0,
+          headersSize: this.#computeResponseHeadersSize(headers),
           // TODO: consider removing from spec.
           bodySize: 0,
           content: {
@@ -325,6 +326,12 @@ export class NetworkRequest {
     };
   }
 
+  #computeResponseHeadersSize(headers: Network.Header[]): number {
+    return headers.reduce((total, header) => {
+      return total + header.name.length + (header.value?.length ?? 0) + 4; // 4 = ': ' + '\r\n'
+    }, 0);
+  }
+
   #isIgnoredEvent(): boolean {
     return (
       this.#requestWillBeSentEvent?.request.url.endsWith('/favicon.ico') ??

tests/test_network.py

@@ -205,6 +205,8 @@ async def test_network_network_response_completed_event_emitted(
         })
 
     resp = await read_JSON_message(websocket)
+    headersSize = compute_response_headers_size(
+        resp["params"]["response"]["headers"])
 
     assert resp == {
         "method": "network.responseCompleted",
@@ -232,7 +234,7 @@ async def test_network_network_response_completed_event_emitted(
                 "headers": ANY_LIST,
                 "mimeType": "text/html",
                 "bytesReceived": ANY_NUMBER,
-                "headersSize": ANY_NUMBER,
+                "headersSize": headersSize,
                 "bodySize": 0,
                 "content": {
                     "size": 0
@@ -319,3 +321,7 @@ async def test_network_before_request_sent_event_with_data_url_emitted(
             "timestamp": ANY_TIMESTAMP
         }
     }
+
+
+def compute_response_headers_size(headers: list[dict[str, str]]) -> int:
+    return sum(sum(len(v) for v in header.values()) + 4 for header in headers)