misc(emulation): Use Nexus 5X emulation real screen size

[exterkamp]

Summary
I'll bite and try to adjust this. I just changed the emulation heights to 660. I wasn't sure if height should be 732 and then screenHeight should be 660 or the other way around? Docs didn't explain which was which, so I just made them both 660 for now.

When changing the emulated device in the frontend it only sends a screenWidth and screenHeight with width & height set to 0:

Note the 660 is derived on the frontend from: 732px - 24px (top bar) - 48px (bottom bar) = 660px

Related Issues/PRs
fixes: #6615

[exterkamp]

There is a lot of height: 732 visibleHeight: 732 etc. in the test/fixtures/traces files, don't know if we need to change those too 🤷‍♂️

[patrickhulce]

I wasn't sure if height should be 732 and then screenHeight should be 660 or the other way around? Docs didn't explain which was which, so I just made them both 660 for now.

https://cs.chromium.org/chromium/src/third_party/blink/public/web/web_device_emulation_params.h?sq=package:chromium&g=0&l=23-33 suggests that width/height is the viewport which can be scrolled maybe using view_position? Not sure either 🤷‍♂️ Either way, copying what frontend does SGTM :)

This is probably going to have some unexpected ramifications down the line. I still think it needs to be done obviously since we're claiming Nexus 5X and the right aspect ratio should be used for it 😃, just trying to think of what could happen.

• Speed Index and anything using ViewportDimensions height will likely change (just offscreen images I think that needs height?)
• Screenshots will be different dimensions (probably doesn't matter to us so much but maybe consumers? @benschwarz @mattzeunert both of yours don't rely on default emulation and our screen size do they?)
• Something else??

[mattzeunert]

Yeah, I'm not relying on the default emulation settings.

Can't think of anything else that would change (as long as the page doesn't render differently based on the changed window height).

[brendankenny]

DZL, do a barrel roll!

[devtools-bot]

DZL is done! Go check it out http://lh-dzl-6932.surge.sh

[brendankenny]

LGTM on the impl side

I'll defer to others on the impact on metrics :)

[patrickhulce]

LGTM too!

For DZL changes, there's just no way this window size is responsible for that drastic TTI shift. Even if it was, people will just have to deal it's a major version bump anyhow 😆

More details on what we gotta do about this persistent problem to come 😞