kernel_log_collector.sh : correct kernel message pattern

The timestamp in the kernel message can have either "+" or "-"
sign. We want to match both of them.

BUG=chromium:226186
TEST=Make sure the script can capture message starting with
"2013-06-19T20:38:58.663410+00:00 localhost kernel: ["

Change-Id: I93647d4fc8b3d796166d2e959b24364de4bc60c5
Reviewed-on: https://gerrit.chromium.org/gerrit/59297
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Yufeng Shen <miletus@chromium.org>
Tested-by: Yufeng Shen <miletus@chromium.org>
diff --git a/crash_reporter/kernel_log_collector.sh b/crash_reporter/kernel_log_collector.sh
index a9d4307..d38479e 100644
--- a/crash_reporter/kernel_log_collector.sh
+++ b/crash_reporter/kernel_log_collector.sh
@@ -9,12 +9,13 @@
 # And only those logs which are within the last YYY seconds of the latest log
 # that has the keyword XXX are printed.
 
-# Kernel log has the format
+# Kernel log has the possible formats:
 # 2013-06-14T16:31:40.514513-07:00 localhost kernel: [    2.682472] MSG MSG ...
+# 2013-06-19T20:38:58.661826+00:00 localhost kernel: [    1.668092] MSG MSG ...
 
 search_key=$1
 time_duration=$2
-msg_pattern="^[0-9-]*T[0-9:.-]* localhost kernel"
+msg_pattern="^[0-9-]*T[0-9:.+-]* localhost kernel"
 
 die() {
   echo "kernel_log_collector: $*" >&2