Print stack traces in child processes when browser tests failed.
The functionality to do this opens up security holes. Currently this was working only for debug Linux builds. However our trybots are release builds, and we need to be able to see stack traces from child processes on all platforms (i.e. to be able to debug the large flakiness that occurred since last week). This is disabled for official builds.
BUG=517488,358267
Review URL: https://codereview.chromium.org/1291553003
Cr-Commit-Position: refs/heads/master@{#343240}
12 files changed
