MD Settings: Allow controlled-button to be used with icons.

chrome/browser/resources/settings/controls/controlled_button.js

Index: chrome/browser/resources/settings/controls/controlled_button.js
diff --git a/chrome/browser/resources/settings/controls/controlled_button.js b/chrome/browser/resources/settings/controls/controlled_button.js
index d1b97231b589064ca4a4d9aa74c0da9445c3a6aa..a9dfd5c8f6c322c9a8b9183ee89c4010833955ad 100644
--- a/chrome/browser/resources/settings/controls/controlled_button.js
+++ b/chrome/browser/resources/settings/controls/controlled_button.js
@@ -18,6 +18,17 @@ Polymer({
       reflectToAttribute: true,
     },
 
+    /**
+     * This attribute takes in a class-name to form an icon button instead of
+     * a paper-button. Note that if this attribute is present, the light dom
+     * content will be ignored.
+     */
+    iconClass: {
+      type: String,
+      value: null,
+      reflectToAttribute: true,
+    },
+
     /** @private */
     controlled_: {
       type: Boolean,