[Bouncer] Update color for userswitcher.

Update color of background. Also update color of drop down icon.

Bug: 247125735
Test: Manual on device
Change-Id: Ice3a78eae451d42d1bea44d1022113bda0b85ecd

packages/SystemUI/res-keyguard/drawable/bouncer_user_switcher_header_bg.xml

@@ -21,11 +21,12 @@
             android:paddingEnd="0dp">
     <item>
         <shape android:shape="rectangle">
-          <solid android:color="?androidprv:attr/colorSurface" />
+          <solid android:color="?androidprv:attr/colorSurfaceHighlight" />
             <corners android:radius="32dp" />
         </shape>
     </item>
     <item
+        android:id="@+id/user_switcher_key_down"
         android:drawable="@drawable/ic_ksh_key_down"
         android:gravity="end|center_vertical"
         android:width="32dp"

packages/SystemUI/src/com/android/keyguard/KeyguardSecurityContainer.java

@@ -1073,6 +1073,11 @@ public class KeyguardSecurityContainer extends FrameLayout {
                         android.R.attr.textColorPrimary));
                 header.setBackground(mView.getContext().getDrawable(
                         R.drawable.bouncer_user_switcher_header_bg));
+                Drawable keyDownDrawable =
+                        ((LayerDrawable) header.getBackground().mutate()).findDrawableByLayerId(
+                                R.id.user_switcher_key_down);
+                keyDownDrawable.setTintList(Utils.getColorAttr(mView.getContext(),
+                        android.R.attr.textColorPrimary));
             }
         }