Roll src/third_party/cros_system_api/ 5c4b60346..304b21ef6 (2 commits)

https://chromium.googlesource.com/chromiumos/platform/system_api.git/+log/5c4b603461a7..304b21ef6d91

$ git log 5c4b60346..304b21ef6 --date=short --no-merges --format='%ad %ae %s'
2017-12-05 xiaochu add UnmountComponent method constant
2017-12-01 ljusten authpolicy: Add GetUserStatusRequest and OU errors

Created with:
  roll-dep src/third_party/cros_system_api chromiumos/platform/system_api.git

Bug=chromium:769970
TEST=None

Change-Id: Id85f7273a891b93370d1d4c2e79a73715242dbc8
Reviewed-on: https://chromium-review.googlesource.com/811628Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Xiaochu Liu <xiaochu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522195}

DEPS

@@ -308,7 +308,7 @@ deps = {
 
   # For Linux and Chromium OS.
   'src/third_party/cros_system_api': {
-      'url': Var('chromium_git') + '/chromiumos/platform/system_api.git' + '@' + 'e494ee7de6e2c99ede5683f0f78e07909f1ba2ed',
+      'url': Var('chromium_git') + '/chromiumos/platform/system_api.git' + '@' + '304b21ef6d9182ebb812cde8f04db17b070bd858',
       'condition': 'checkout_linux',
   },