GitLab

Also:
- upstream some "ifdef(OS_WIN)" by moving stability_debugging_win.{h,cc} to stability_debugging.{h,cc}.
- enclose components/browser_watcher/BUILD.gn targets in "if (is_win) {}" as the dependency from components/metrics started causing win only targets to be built on other platforms.

BUG=620813

Review-Url: https://codereview.chromium.org/2531123002
Cr-Commit-Position: refs/heads/master@{#439536}