Unrevert r64676 "Part 4/4 of immutable Extension refactor: Kill Extension::StaticData and put"

Original CL:
Part 4/4 of immutable Extension refactor: Kill Extension::StaticData and put
its guts into Extension.

BUG=56558
TEST=no functional change

Review URL: http://codereview.chromium.org/4200005

Review URL: http://codereview.chromium.org/4277002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64767 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed