Convert GN source_set to static_library.

This improves the build time somewhat.
BUG=http://crbug.com/627637
R=rtoy@google.com

Review URL: https://codereview.webrtc.org/2171553002 .
2 files changed
tree: ef4fe6cdc18ab5de743fa292fd1e47a9685a855b
  1. LICENSE
  2. OWNERS
  3. README.chromium
  4. codereview.settings
  5. dl/