I'm guessing the root cause is this:
---
/b/s/w/ioajsmeisv/layout-test-results/fast/dom/Window/window-constructor-expected.txt
+++
/b/s/w/ioajsmeisv/layout-test-results/fast/dom/Window/window-constructor-actual.txt
@@ -0,0 +1,5 @@
+This is a testharness.js-based test.
+[FAIL] Test Window and its prototype chain's constructors.
+ assert_equals: WindowProperties constructor is EventTarget. expected
function "function EventTarget() { [native code] }" but got function
"function WindowProperties() { [native code] }"
+Harness: the test ran to completion.
+
Though *why* it's failing, I don't know off hand and will need to dig into
it. It does seem worth fixing that.
Daniel
On Mon, 15 Jul 2024 at 23:29, Leszek Swirski <lesz...@chromium.org> wrote:
> I'm not saying that it's subtle and hard to get right, any more so than
> any other code we ship at least, I'm saying that it's a full separate code
> path and behaviour that we would be shipping to users without running
> locally. The difficulties I'm having on android are because of build
> config/dependency issues.
>
> For "how much performance", I'm currently trying to enable it on Android
> because it would improve Search page load by what they estimate to be ~24
> SWE-years worth of improvement (Kentaro has a calculation in this doc
> <https://docs.google.com/document/d/1QwzaNvSwkXeR2_Du5SnXNKPqA3ZTrh8bBK0kbC5T4BI/edit?tab=t.0>).
> Also +Kouhei Ueno <kou...@google.com> who has been looking into the
> impact of context setup on page load, and +Camillo Bruni
> <cbr...@chromium.org> who looked at the performance with Scott.
>
> On Tue, 16 Jul 2024, 02:43 Nico Weber, <tha...@chromium.org> wrote:
>
>> If the code path behind use_v8_context_snapshot is subtle and hard to get
>> right, it sounds like there's our second reason for not having it, right
>> there :)
>>
>> How much performance does the blink snapshot buy us? Is it possible to
>> get some of that with less expensive techniques?
>>
>> (+sky who I think looked at this at some point.)
>>
>> On Monday, July 15, 2024 at 2:54:35 PM UTC-4 Leszek Swirski wrote:
>>
>>> +Michael Lippautz <mlippa...@google.com>
>>>
>>> I'm not sure we should do this for build time reasons alone.
>>> `use_v8_context_snapshot` is the default behaviour in shipping browsers,
>>> and it makes the renderer take quite a different path during page load /
>>> navigation. If we disable it in regular builds, then regular builds
>>> (including all the dchecks!) won't be running and texting the same code
>>> that we're shipping.
>>>
>>> The fact that tests are failing with this flag change should be a huge
>>> flashing red light about this proposal - if we make the tests not test the
>>> code we're shipping, then we risk it breaking without us noticing. Indeed,
>>> I've been trying to turn this flag on for Android, and have been struggling
>>> to do so.
>>>
>>> - Leszek
>>>
>>>
>>> On Mon, 15 Jul 2024, 20:25 Dave Tapuska, <dtapu...@chromium.org> wrote:
>>>
>>>> Have you thought about setting gn config v8_use_external_startup_data
>>>> on any bots?
>>>>
>>>> I don't know why they are failing. The window constructor one is weird
>>>> as well because the prototype chain is different...
>>>>
>>>> dave.
>>>>
>>>> On Mon, Jul 15, 2024 at 2:13 PM Nico Weber <tha...@chromium.org> wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> use_v8_context_snapshot causes us to build lots of files (blink +
>>>>> dependencies) twice on bots that cross-compiler (win/arm64, android, etc).
>>>>>
>>>>> We'd like to turn off use_v8_context_snapshot in regular release
>>>>> builds by default, and only keep it enabled in is_official_build builds.
>>>>>
>>>>> However, a small number of tests, almost all of
>>>>> them inspector-protocol tests, fail if I try this:
>>>>> https://chromium-review.googlesource.com/c/chromium/src/+/5704136
>>>>>
>>>>> That's surprising to me. I would've expected use_v8_context_snapshot
>>>>> to not change behavior.
>>>>>
>>>>> Does anyone have an idea why this might happen?
>>>>>
>>>>> Thanks,
>>>>> Nico
>>>>>
>>>>> --
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>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CADZ1XibPV%3Dd448fckQeYFaO617_9aahsxysAjMEdQ4sy%3DQw4kQ%40mail.gmail.com?utm_medium=email&utm_source=footer>
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