[SmartLock] Inform base EasyUnlockService once feature state is initialized.

When MultiDeviceSetupClient was integrated, a subtle bug was also introduced.
Its default state for all features is kProhibitedByPolicy, which made the
initial call to IsAllowed() in EasyUnlockService::UpdateAppState() return false,
since MultiDeviceSetupClient is still being initialized when this call is made.
EasyUnlockService remained not fully set up because of this issue, preventing
its PowerManager from being instantiated. This CL simply informs the base
class when MultiDeviceSetupClient is fully initialized, in order to complete
EasyUnlockService initialization.

Bug: 952496, 950758
Change-Id: Ibb5741c3dc9d3ec0fd5fc8d1cac78275ea0fb2b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1564327
Commit-Queue: Ryan Hansberry <hansberry@chromium.org>
Commit-Queue: Jeremy Klein <jlklein@chromium.org>
Auto-Submit: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Jeremy Klein <jlklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650544}

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

@@ -466,6 +466,7 @@ void EasyUnlockServiceRegular::OnFeatureStatesChanged(
 
   feature_state_ = it->second;
   LoadRemoteDevices();
+  UpdateAppState();
 }
 
 void EasyUnlockServiceRegular::ShowChromebookAddedNotification() {