[webcrypto] Add AES-GCM using NSS.

This requires NSS version 3.15 or greater. Since Linux Chrome is using the system NSS it may not work for Linux users unless they have a more recent NSS version. Mac and Windows builds however are not affected by this and it should just work.

BUG=245025

Review URL: https://codereview.chromium.org/115653002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244845 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed