Make POSIX SIGTERM/SIGINT/SIGHUP handler async signal safe.
* Don't use LOG/CHECK.  Replace with RAW_LOG/DCHECK (newly added to logging.h)
* Don't directly post a task to the UI loop.  Write to a magic pipe.  Read this from a separate thread which will post to a task to the UI loop.
BUG=http://crbug.com/29240

Review URL: http://codereview.chromium.org/460094

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34036 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed