[SmartLock] Improve logs around setting devices.

In logs from Smart Lock bug reports, I have observed remote devices
being 'successfully' set in EasyUnlockServiceRegular and
ProximityAuthSystem, quickly followed by a message from
ProximityAuthSystem 'User... does not have a Smart Lock host device'.
This change improves logging around setting remote devices in order
to better diagnose the issue if it's observed again.

Bug: 953027
Change-Id: Id46c62aba4e441b3fcb4c32332b392a77e947cd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1617086
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Jeremy Klein <jlklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661039}

chrome/browser/chromeos/login/easy_unlock/easy_unlock_service_regular.cc

@@ -129,7 +129,7 @@ void EasyUnlockServiceRegular::LoadRemoteDevices() {
       multidevice_setup::mojom::FeatureState::kEnabledByUser) {
     // OnFeatureStatesChanged() will call back on this method when feature state
     // changes.
-    PA_LOG(VERBOSE) << "Smart Lock is disabled; aborting.";
+    PA_LOG(VERBOSE) << "Smart Lock is not enabled by user; aborting.";
     SetProximityAuthDevices(GetAccountId(), multidevice::RemoteDeviceRefList(),
                             base::nullopt /* local_device */);
     return;
@@ -149,6 +149,8 @@ void EasyUnlockServiceRegular::LoadRemoteDevices() {
     pref_manager_->SetEasyUnlockEnabledStateSet();
     LogSmartLockEnabledState(SmartLockEnabledState::ENABLED);
   } else {
+    PA_LOG(ERROR) << "Smart Lock is enabled by user, but no unlock key is "
+                     "present; aborting.";
     SetProximityAuthDevices(GetAccountId(), multidevice::RemoteDeviceRefList(),
                             base::nullopt /* local_device */);
 
@@ -175,7 +177,11 @@ void EasyUnlockServiceRegular::LoadRemoteDevices() {
 void EasyUnlockServiceRegular::UseLoadedRemoteDevices(
     const multidevice::RemoteDeviceRefList& remote_devices) {
   // When EasyUnlock is enabled, only one EasyUnlock host should exist.
-  DCHECK(remote_devices.size() == 1u);
+  if (remote_devices.size() != 1u) {
+    PA_LOG(ERROR) << "There should only be 1 Smart Lock host, but there are: "
+                  << remote_devices.size();
+    NOTREACHED();
+  }
 
   SetProximityAuthDevices(GetAccountId(), remote_devices,
                           device_sync_client_->GetLocalDeviceMetadata());
@@ -239,9 +245,21 @@ void EasyUnlockServiceRegular::UseLoadedRemoteDevices(
                       multidevice::SoftwareFeatureState::kEnabled;
     dict->SetBoolean(key_names::kKeyUnlockKey, unlock_key);
 
+    PA_LOG(VERBOSE) << "Storing RemoteDevice: { "
+                    << "name: " << device.name()
+                    << ", unlock_key: " << unlock_key
+                    << ", id: " << device.GetTruncatedDeviceIdForLogs()
+                    << " }.";
     device_list->Append(std::move(dict));
   }
 
+  if (device_list->GetSize() != 2u) {
+    PA_LOG(ERROR) << "There should only be 2 devices persisted, the host and "
+                     "the client, but there are: "
+                  << device_list->GetSize();
+    NOTREACHED();
+  }
+
   SetStoredRemoteDevices(*device_list);
 }
 
@@ -250,7 +268,6 @@ void EasyUnlockServiceRegular::SetStoredRemoteDevices(
   std::string remote_devices_json;
   JSONStringValueSerializer serializer(&remote_devices_json);
   serializer.Serialize(devices);
-  PA_LOG(VERBOSE) << "Setting RemoteDevices:\n  " << remote_devices_json;
 
   DictionaryPrefUpdate pairing_update(profile()->GetPrefs(),
                                       prefs::kEasyUnlockPairing);

chromeos/components/proximity_auth/proximity_auth_system.cc

@@ -59,6 +59,11 @@ void ProximityAuthSystem::SetRemoteDevicesForUser(
     const AccountId& account_id,
     const chromeos::multidevice::RemoteDeviceRefList& remote_devices,
     base::Optional<chromeos::multidevice::RemoteDeviceRef> local_device) {
+  PA_LOG(VERBOSE) << "Setting devices for user " << account_id.Serialize()
+                  << ". Remote device count: " << remote_devices.size()
+                  << ", Local device: ["
+                  << (local_device.has_value() ? "present" : "absent") << "].";
+
   remote_devices_map_[account_id] = remote_devices;
   local_device_map_.emplace(account_id, *local_device);