update_engine: Indicate existence of owner instead of owner's email in log.

Logging the device owner's email is possibly a PII, so instead log
whether the device has a owner as a boolean value.

Enterprise devices do not have a device owner.

The variable var_has_owner is dependent on DevicePolicy::GetOwner().

BUG=chromium:973108
TEST=unittest

Change-Id: I535f664a4fcf75c6102346b8566605710b062255
Reviewed-on: https://chromium-review.googlesource.com/1660911
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Ready: Jae Hoon Kim <kimjae@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/update_manager/chromeos_policy_unittest.cc b/update_manager/chromeos_policy_unittest.cc
index fb8c789..25c91fa 100644
--- a/update_manager/chromeos_policy_unittest.cc
+++ b/update_manager/chromeos_policy_unittest.cc
@@ -1365,7 +1365,7 @@
 
   // Override specific device policy attributes.
   fake_state_.device_policy_provider()->var_au_p2p_enabled()->reset(nullptr);
-  fake_state_.device_policy_provider()->var_owner()->reset(nullptr);
+  fake_state_.device_policy_provider()->var_has_owner()->reset(new bool(false));
   fake_state_.device_policy_provider()->var_http_downloads_enabled()->reset(
       new bool(false));
 
@@ -1610,7 +1610,7 @@
 
 TEST_F(UmChromeOSPolicyTest, P2PEnabledAllowedDeviceEnterpriseEnrolled) {
   fake_state_.device_policy_provider()->var_au_p2p_enabled()->reset(nullptr);
-  fake_state_.device_policy_provider()->var_owner()->reset(nullptr);
+  fake_state_.device_policy_provider()->var_has_owner()->reset(new bool(false));
 
   bool result;
   ExpectPolicyStatus(EvalStatus::kSucceeded, &Policy::P2PEnabled, &result);