Move Flutter Gallery to dev/integration_tests/ as it is an older copy used only for testing. The current version of the Flutter Gallery now lives in https://github.com/flutter/gallery.
* Update project.pbxproj files to say Flutter rather than Chromium
Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.
* Update the copyright notice checker to require a standard notice on all files
* Update copyrights on Dart files. (This was a mechanical commit.)
* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.
Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).
* Clean up the copyrights in non-Dart files. (Manual edits.)
Also, make sure templates don't have copyrights.
* Fix some more ORGANIZATIONNAMEs
Previously, I used the Android emulator for testing and everything
seemed to work fine with stdout (if I remember correctly). But our
devicelab uses real Android devices and the warnings are routed to
stderr. Hence change stdout to stderr in the test.
## Description
Print actionable warnings if `flutter drive` (where most of our performance benchmarks come from) is run in debug mode and it tries to gather benchmarks using `traceAction`.
## Related Issues
https://github.com/flutter/flutter/issues/30625
## Tests
I added the following tests:
* drive_perf_debug_warning devicelab test
