Make VPN key icon visible in dark theme.

Bug: 129463858
Test: manual
Change-Id: I423aeaf5296f53e44817b1a92138c3ba3dff0786
diff --git a/packages/VpnDialogs/src/com/android/vpndialogs/ConfirmDialog.java b/packages/VpnDialogs/src/com/android/vpndialogs/ConfirmDialog.java
index 72ce9c4..989470f 100644
--- a/packages/VpnDialogs/src/com/android/vpndialogs/ConfirmDialog.java
+++ b/packages/VpnDialogs/src/com/android/vpndialogs/ConfirmDialog.java
@@ -29,6 +29,7 @@
 import android.text.Html;
 import android.text.Html.ImageGetter;
 import android.util.Log;
+import android.util.TypedValue;
 import android.view.View;
 import android.widget.Button;
 import android.widget.TextView;
@@ -111,8 +112,16 @@
     @Override
     public Drawable getDrawable(String source) {
         // Should only reach this when fetching the VPN icon for the warning string.
-        Drawable icon = getDrawable(R.drawable.ic_vpn_dialog);
+        final Drawable icon = getDrawable(R.drawable.ic_vpn_dialog);
         icon.setBounds(0, 0, icon.getIntrinsicWidth(), icon.getIntrinsicHeight());
+
+        final TypedValue tv = new TypedValue();
+        if (getTheme().resolveAttribute(android.R.attr.textColorPrimary, tv, true)) {
+            icon.setTint(getColor(tv.resourceId));
+        } else {
+            Log.w(TAG, "Unable to resolve theme color");
+        }
+
         return icon;
     }