Add a Watcher interface.

Unlike DirectoryWatcher, this interface isn't directory-specific. This
also allows ResubscribableDirectoryWatcher to become
ResubscribableWatcher, which will make it easier to implement
single-file watching.

See #17

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//1180233003.
13 files changed
tree: 268edff8cc4fe0620362a8cbffe45f853af61885
  1. example/
  2. lib/
  3. test/
  4. .gitignore
  5. .status
  6. CHANGELOG.md
  7. codereview.settings
  8. LICENSE
  9. pubspec.yaml
  10. README.md
README.md

A file system watcher.

It monitors changes to contents of directories and sends notifications when files have been added, removed, or modified.