Enable the keyboard to show the popup keyboard for inputting accented characters.

chrome/browser/resources/keyboard/main.css

Index: chrome/browser/resources/keyboard/main.css
diff --git a/chrome/browser/resources/keyboard/main.css b/chrome/browser/resources/keyboard/main.css
index 0a1bd6f8db0d0622a02c76bf66eeb7a14efbbe11..6e6ea6bd91b0409d8a42c37a26de18239832ab1f 100644
--- a/chrome/browser/resources/keyboard/main.css
+++ b/chrome/browser/resources/keyboard/main.css
@@ -70,6 +70,15 @@ div.row > div {
   text-align: left;
 }
 
+.popup {
+  background: rgba(30, 30, 30, 0.7);
+  border: 1px solid rgba(50, 50, 50, 0.8);
+  padding-right: 5px;
+  position: absolute;
+  -webkit-border-radius: 4px;
+  -webkit-box-shadow: 5px 5px 3px rgba(50, 50, 200, 0.3);
+}
+
 .button {
   background: -webkit-linear-gradient(#5a616f, #505662);
 }
@@ -101,6 +110,15 @@ div.row > div {
   top: 0;
 }
 
+.key.popupkey {
+  background: rgba(0, 0, 0, 0);
+  border: 1px solid rgba(0, 0, 0, 0);
+}
+
+.key.popupkey.highlighted {
+  background: rgba(20, 20, 200, 0.3);
+}
+
 .r0 {
   background: -webkit-linear-gradient(#5a616f, #505662);
 }