[MacOS] Add support for creating and presenting platform views.

[RichardJCai]

Add support for:

1. Registering view factories.
2. Creating / Disposing platform views.
3. Presenting platform views in FlutterGLCompositor

Will add follow up PR for static thread merging, there may be visual bugs since raster/ui threads are not merged.

[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[cyanglaz]

We are also missing tests in this PR.

[cyanglaz]

LGTM % nits, assuming @iskakaushik LGTMed as well.
Thanks for adding tests!

[iskakaushik]

Please don't merge this until i've taken a look :-) I think the public API here needs a little more scrutiny.

[RichardJCai]

I did a first pass. I'm confused by what's expected to work as a result of this PR though, given that there are references to adding public API but this PR doesn't appear to actually add any public API.

Thanks for the review! I'll update this on Friday.

[RichardJCai]

@stuartmorgan @iskakaushik
I'm trying to update this PR but whenever I try building with a local engine, I'm getting the following error.

Building macOS application...
2021-01-18 16:42:24.578 testapp3[52826:2671766] Failed to find path for "flutter_assets"
2021-01-18 16:42:24.578 testapp3[52826:2671766] Failed to find path for "flutter_assets"
embedder.cc (764): 'FlutterEngineInitialize' returned 'kInvalidArguments'. The assets path in the Flutter project arguments was missing.
2021-01-18 16:42:24.578 testapp3[52826:2671766] Failed to initialize Flutter engine: error 2

First ran into after rebasing this branch ontop of master but it seems like I'm running into on master as well with a local engine.

Tried following the suggestions in this issue flutter/flutter#72608, ie upgrading and doing a new project but none seem to work with a local engine.

flutter run -d macos seems to work fine.

Anyone have any ideas whats wrong here?

[stuartmorgan]

I wouldn't have expected a local engine to have any effect on App.framework copying. I'll see if I can reproduce locally and follow up in flutter/flutter#72608

[google-cla]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[jmagman]

I'm getting the same failures as https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket.appspot.com/8857625998621949056/+/steps/build_host_debug_unopt/0/stdout locally. Can you fix those up and see if you are still reproducing flutter/flutter#72608?

[RichardJCai]

I'm getting the same failures as https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket.appspot.com/8857625998621949056/+/steps/build_host_debug_unopt/0/stdout locally. Can you fix those up and see if you are still reproducing flutter/flutter#72608?

Never mind, I was able to solve the problem by recloning the repos and setting up the environment again.

[iskakaushik]

Hey @RichardJCai , thanks for continuing to work and make progress on this PR. Given the inactivity over the last week, I'm closing this. Feel free to open a new PR once you get a chance to address the failing pre-submit checks and tag me. Thanks!

[RichardJCai]

Hey @RichardJCai , thanks for continuing to work and make progress on this PR. Given the inactivity over the last week, I'm closing this. Feel free to open a new PR once you get a chance to address the failing pre-submit checks and tag me. Thanks!

Sorry tried to address the PR comments but I still can't seem to get my engine environment set up for some reason.

[cbenhagen]

@RichardJCai did you have a chance to fix your environment? I know you probably already checked this but I once got this exact same error message when the underlying issue was in fact a build error in my dart code. Can you maybe post a verbose output of your build with the local engine? I'd be happy to help you debug your environment as good as I can. Here on or on Discord (cben#2483).