Reset Opacity when starting Voice Interaction OOBE

Reset login container opacity before voice interaction OOBE since the
container could be transparent after unlock animation.

BUG=b/64123072

Change-Id: I38b7d176d83f122bf680674f8ee7ebea5a0054fd
Reviewed-on: https://chromium-review.googlesource.com/591634Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Yue Li <updowndota@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490776}

chrome/browser/chromeos/login/ui/login_display_host_impl.cc

@@ -1295,6 +1295,13 @@ void LoginDisplayHostImpl::DisableRestrictiveProxyCheckForTest() {
 
 void LoginDisplayHostImpl::StartVoiceInteractionOobe() {
   is_voice_interaction_oobe_ = true;
+
+  // Lock container can be transparent after lock screen animation.
+  aura::Window* lock_container = ash::Shell::GetContainer(
+      ash::Shell::GetPrimaryRootWindow(),
+      ash::kShellWindowId_LockScreenContainersContainer);
+  lock_container->layer()->SetOpacity(1.0);
+
   finalize_animation_type_ = ANIMATION_NONE;
   StartWizard(chromeos::OobeScreen::SCREEN_VOICE_INTERACTION_VALUE_PROP);
 }