Add support for mark as unread.

app/src/main/java/org/thoughtcrime/securesms/util/views/DarkOverflowToolbar.java

@@ -0,0 +1,39 @@
+package org.thoughtcrime.securesms.util.views;
+
+import android.content.Context;
+import android.graphics.PorterDuff;
+import android.util.AttributeSet;
+
+import androidx.annotation.Nullable;
+import androidx.appcompat.widget.Toolbar;
+
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.util.ThemeUtil;
+
+/**
+ * It seems to be impossible to tint the overflow icon in an ActionMode independently from the
+ * default toolbar overflow icon. So we default the overflow icon to white, then we can use this
+ * subclass to make it the correct themed color for most use cases.
+ */
+public class DarkOverflowToolbar extends Toolbar {
+  public DarkOverflowToolbar(Context context) {
+    super(context);
+    init();
+  }
+
+  public DarkOverflowToolbar(Context context, @Nullable AttributeSet attrs) {
+    super(context, attrs);
+    init();
+  }
+
+  public DarkOverflowToolbar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
+    super(context, attrs, defStyleAttr);
+    init();
+  }
+
+  private void init() {
+    if (getOverflowIcon() != null) {
+      getOverflowIcon().setColorFilter(ThemeUtil.getThemedColor(getContext(), R.attr.icon_tint), PorterDuff.Mode.SRC_ATOP);
+    }
+  }
+}