c5e0858a01
This PR adds `PlatformDispatcher.scheduleWarmUpFrame`. This PR is needed for the follow up changes: * The framework will switch to using this function to render warmup frames in https://github.com/flutter/flutter/pull/143290. * Then the engine will finally be able to switch to multiview pipeline with no regression on startup timing in https://github.com/flutter/engine/pull/49950. For why the warm up frame must involve the engine to render, see https://github.com/flutter/flutter/issues/142851. ## Pre-launch Checklist - [ ] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [ ] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [ ] I read and followed the [Flutter Style Guide] and the [C++, Objective-C, Java style guides]. - [ ] I listed at least one issue that this PR fixes in the description above. - [ ] I added new tests to check the change I am making or feature I am adding, or the PR is [test-exempt]. See [testing the engine] for instructions on writing and running engine tests. - [ ] I updated/added relevant documentation (doc comments with `///`). - [ ] I signed the [CLA]. - [ ] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/wiki/Tree-hygiene#overview [Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene [test-exempt]: https://github.com/flutter/flutter/wiki/Tree-hygiene#tests [Flutter Style Guide]: https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo [C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style [testing the engine]: https://github.com/flutter/flutter/wiki/Testing-the-engine [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/wiki/Chat