DevTools: Fix build after r183969

The "extensions" module is now autostarted.

TBR=pfeldman

Review URL: https://codereview.chromium.org/663023004

git-svn-id: svn://svn.chromium.org/blink/trunk@183980 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: remove style reuse from flamechart clients, prepare it to become a component.

BUG=417275

Review URL: https://codereview.chromium.org/668683002

git-svn-id: svn://svn.chromium.org/blink/trunk@183990 bbb929c8-8fbe-4397-9dbb-9b2b20218538