Capture content of request/response.
Changes about this cl:
1. The body of request will be written used by methods of `IOSink`. Each
operation will emit a single event on the same timeline task. Add() will
accept List<int> and write() works with strings. The data will remain
the same as what user has passed. With that being said, data coming from
add() will show a list of integers and a string representation if
write() is used.
2. The timeline of `HttpClientResponse` will be a child timeline of
corresponding `HttpClientRequest`. It will be recorded only if parent
request is recorded and logging flag is still set. If the flag is on
after the request is sent, the response will not be monitored.
3. `HttpClientResponse` is simply a stream. The timeline starts when
the response is received. But it is possible that users doesn't
read the content and close the program. In this case, timeline never
gets a proper close event. To have a close event, users has to call
listen().
4. This also fixes verify_http_time_line_test.dart. It was broken
and not checking correct events because of a typo.
Bug: https://github.com/dart-lang/sdk/issues/42952
Change-Id: I884db6405264a3ad9a03cecc8f5445dad4fb3e31
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/157567
Commit-Queue: Zichang Guo <zichangguo@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Zichang Guo
7d7c883890