Consolidate code monitoring low memory kills and OOM kills to MemoryKillsMonitor on ChromeOS
Rename OomKillsMonitor to MemoryKillsMonitor and move it from
arc namespace to memory namespace. Now it is responsible for
1. Log OOM kill events by listening to kernel messages (in a dedicated thread).
2. Log low memory kill events when TabManager kills processes (called from UI thread).
It logs those events to
1. Chrome UMA
2. A local file if --memory-kills-log is given
It starts a new monitoring session when a new BrowserProcess is created.
BUG=none
TEST=manual
Review-Url: https://codereview.chromium.org/2527973003
Cr-Commit-Position: refs/heads/master@{#435743}
16 files changed
