* build: enable gn check for //electron:electron_lib
* ci: add gn check step
* ci: set depot_tools path
* chrome_key_systems_provider.h nogncheck
* chore: fix gn check errors on windows
* chore: gn check //electron:electron_app
* chore: fix cpplint 'include_what_you_use' warnings
Typically by including <memory>, <utility> etc.
* chore: fix 'static/global string constant' warning
Use C style strings instead of std::string.
Style guide forbids non-trivial static / global variables. https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
/home/charles/electron/electron-gn/src/electron/script/cpplint.js
* refactor: remove global string variables.
Fix 'global string variables are not permitted' linter warnings
by using the base::NoDestructor<> wrapper to make it explicit that
these variables are never destroyed.
The style guide's take on globals with nontrivial destructors:
https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
* fix: initializer error introduced in last commit
* fix: remove WIP file that was included by accident
* fix: include order
* fix: include order
* fix: include order
* fix: include order, again
