Options2: Pull the trigger.

chrome/browser/resources/options2/search_engine_manager.css

+.search-engine-list > div {
+  display: -webkit-box;
+}
+
+.search-engine-list .favicon {
+  padding: 1px 7px 0px 7px;
+  height: 16px;
+}
+
+.search-engine-list .name-column {
+  -webkit-box-align: center;
+  -webkit-padding-end: 1ex;
+  box-sizing: border-box;
+  display: -webkit-box;
+  width: 37%;
+}
+
+.search-engine-list .name-column :last-child {
+  -webkit-box-flex: 1;
+}
+
+.search-engine-list .keyword-column {
+  -webkit-padding-end: 1ex;
+  box-sizing: border-box;
+  width: 26%;
+}
+
+.search-engine-list .url-column {
+  box-sizing: border-box;
+  width: 37%;
+}
+
+.search-engine-list .keyword-column,
+.search-engine-list .url-column {
+  color: #666666;
+}
+
+.search-engine-list .default .name-column,
+.search-engine-list .default .keyword-column {
+  font-weight: bold;
+}
+
+/* For temporary Make Default button */
+.search-engine-list .url-column {
+  display: -webkit-box;
+  -webkit-box-align: center;
+}
+
+.search-engine-list .url-column :first-child {
+  -webkit-box-flex: 1;
+}
+
+.search-engine-list .url-column button {
+  -webkit-margin-start: 3px;
+  background: #8aaaed;
+  color: #fff;
+  margin-top: 0;
+}
+
+.search-engine-list > :not(:hover):not([editing]) .url-column button {
+  display: none;
+}
+
+/* End temporary Make Default button styling */