Move the last extensions/common unit tests to extensions_unittests
They don't need to run in Chrome's unit_tests suite any more.
* Move ExtensionL10UtilTest
* Move FileUtilTest
* Keep browser action and page action tests in Chrome, since those are
Chrome-specific concepts
This CL depends on
https://codereview.chromium.org/565423003/ for cleanup
of _manifest_features.json
BUG=
397165
TEST=extensions_unittests, unit_tests
Committed:
https://crrev.com/f765cb48310ab9d5dcaba7ec118115a32dd7c964
Cr-Commit-Position: refs/heads/master@{#295605}