Add base class cr.ui.BubbleButton for options.ControlledSettingIndicator

chrome/browser/resources/shared/css/bubble_button.css

Index: chrome/browser/resources/shared/css/bubble_button.css
diff --git a/chrome/browser/resources/shared/css/bubble_button.css b/chrome/browser/resources/shared/css/bubble_button.css
new file mode 100644
index 0000000000000000000000000000000000000000..5f37ed207069018fd143c3d548cceafebd76d899
--- /dev/null
+++ b/chrome/browser/resources/shared/css/bubble_button.css
@@ -0,0 +1,20 @@
+/* Copyright (c) 2013 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+.bubble-button {
+  display: inline-block;
+  height: 0;
+  line-height: 1;
+  vertical-align: middle;
+  width: 16px;
+}
+
+.bubble-button > div {
+  background-size: 16px;
+  height: 16px;
+  position: relative;
+  top: -8px;
+  width: 16px;
+}