This writes a generator for GYP actions to run Ninja for script targets. This does not yet include the code that actually writes the corresponding ninja files.

The GYP code also needed some output directory generation code, so this was consolidated in filesystem_utils and referenced from the existing place.

BUG=322244
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/80463004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236837 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236837
Add missing copyright statement to ui_strings.gyp.

BUG=None
TEST=None
TBR=ben@chromium.org

Review URL: https://codereview.chromium.org/83513006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236838 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236838
Add "ninja show" and "ninja refresh" targets to GN build.

"ninja show" will print out the build arguments for when you can't remember the configuration of your output directory.

"ninja refresh" ignores dependencies and regenerates the ninja files.

R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/82923005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236840 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236840