update_engine: Log the rootfs and stateful partition's lsb-release

postinst cannot not do this anymore, so we need to log it in the UE itself.

BUG=chromium:786225
TEST=cros_flash two times and made sure they are logged.

Change-Id: I2fbc593f55e6425127de283c78e4170460bac0d9
Reviewed-on: https://chromium-review.googlesource.com/791515
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Alex Deymo <deymo@google.com>
diff --git a/update_attempter.cc b/update_attempter.cc
index f8161a4..4fef9ce 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -1032,6 +1032,15 @@
     SetStatusAndNotify(UpdateStatus::UPDATE_AVAILABLE);
   } else if (type == DownloadAction::StaticType()) {
     SetStatusAndNotify(UpdateStatus::FINALIZING);
+  } else if (type == FilesystemVerifierAction::StaticType()) {
+    // Log the system properties before the postinst and after the file system
+    // is verified. It used to be done in the postinst itself. But postinst
+    // cannot do this anymore. On the other hand, these logs are frequently
+    // looked at and it is preferable not to scatter them in random location in
+    // the log and rather log it right before the postinst. The reason not do
+    // this in the |PostinstallRunnerAction| is to prevent dependency from
+    // libpayload_consumer to libupdate_engine.
+    LogImageProperties();
   }
 }