[CrOs] Fix icon color for system label button on login/lock screen

Bug: 1104336
Change-Id: I7da10e535330b0f583d9998b334e41061fe0cd1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2536437Reviewed-by: Thomas Tellier <tellier@google.com>
Reviewed-by: Min Chen <minch@chromium.org>
Commit-Queue: Thomas Tellier <tellier@google.com>
Cr-Commit-Position: refs/heads/master@{#827361}

ash/login/ui/system_label_button.cc

@@ -51,11 +51,12 @@ SystemLabelButton::SystemLabelButton(PressedCallback callback,
   SetPaintToLayer();
   layer()->SetFillsBoundsOpaquely(false);
   if (display_type == DisplayType::ALERT_WITH_ICON) {
-    SetImage(views::Button::STATE_NORMAL,
-             CreateVectorIcon(
-                 kLockScreenAlertIcon,
-                 AshColorProvider::Get()->GetContentLayerColor(
-                     AshColorProvider::ContentLayerType::kIconColorAlert)));
+    SetImage(
+        views::Button::STATE_NORMAL,
+        CreateVectorIcon(
+            kLockScreenAlertIcon,
+            AshColorProvider::Get()->GetContentLayerColor(
+                AshColorProvider::ContentLayerType::kButtonIconColorPrimary)));
   }
   SetTextSubpixelRenderingEnabled(false);
   SetInkDropMode(InkDropMode::ON);