crash-reporter: Test boot_mode in crash_sender

Test that crash reports from machines in dev mode now have a "boot_mode"
annotation.

BUG=chromium-os:33947
TEST=Ran logging_CrashSender autotest
CQ-DEPEND=I30d58885e41f2c32e32b7b0f691ed2e5d14f2e3c

Change-Id: If4c52f52b9b3cbc6e4ef999fb68a1a75a2aad374
Reviewed-on: https://gerrit.chromium.org/gerrit/33248
Tested-by: Michael Krebs <mkrebs@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Commit-Ready: Michael Krebs <mkrebs@chromium.org>
2 files changed