Options2: Pull the trigger.

chrome/browser/resources/options2/chromeos/change_picture_options.css

+#images-grid {
+  -webkit-user-drag: none;
+  -webkit-user-select: none;
+  margin: 10px;
+  outline: none;
+  padding: 10px;
+}
+
+#images-grid * {
+  margin: 0;
+  padding: 0;
+}
+
+#images-grid img {
+  background-color: white;
+  height: 64px;
+  vertical-align: middle;
+  width: 64px;
+}
+
+#images-grid [role=listitem] {
+  border-radius: 4px;
+  border: 1px solid rgba(0, 0, 0, 0.15);
+  display: inline-block;
+  margin: 10px;
+  padding: 3px;
+}
+
+#images-grid [selected] {
+  border: 2px solid #06c;
+  padding: 2px;
+}