Fix device_event_log component build, make NonThreadSafe (Take 2)

This patch includes the correct GN changes.

This CL does the following:
* Fixes the component build
* Limits the length of LogEntry strings
* Cleans up the code a little to help with crash debugging

BUG=479095
For device_event_log gypi:
TBR=reillyg@chromium.org

Review URL: https://codereview.chromium.org/1140643002

Cr-Commit-Position: refs/heads/master@{#329320}
10 files changed