* 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
https://github.com/flutter/flutter/issues/17956
* Add a `debugInstrumentAction()` method that will wrap an action
in a stopwatch and print the time it took to run the action.
* Add a global `debugInstrumentationEnabled` that will control
whether `debugInstrumentAction()` does anything (even in debug
builds).
* Add some basic instrumentation to `registerServiceExtension()`
* Temporarily enable the `debugInstrumentationEnabled` flag in the
Gallery to give us better visibility into what's happening in
https://github.com/flutter/flutter/issues/17956
