Add the most recent crash report IDs to feedback reports

Adds the IDs of crashes that occurred within the last hour before sending the
feedback report, making sure that these IDs don't end up in the system_logs.txt
file for privacy reasons.

BUG=613606

Review-Url: https://codereview.chromium.org/2242833003
Cr-Commit-Position: refs/heads/master@{#418351}
7 files changed