Fix the UK keyboard overlay Enter key shape

chrome/browser/resources/chromeos/keyboard_overlay.css

Index: chrome/browser/resources/chromeos/keyboard_overlay.css
diff --git a/chrome/browser/resources/chromeos/keyboard_overlay.css b/chrome/browser/resources/chromeos/keyboard_overlay.css
index 7b89b2283015d6ff9275d3f6d0d5c62f518765a7..a364742bd94204ff9f744b57c4dbde5a249614a2 100644
--- a/chrome/browser/resources/chromeos/keyboard_overlay.css
+++ b/chrome/browser/resources/chromeos/keyboard_overlay.css
@@ -60,7 +60,6 @@ body {
 
 .keyboard-overlay-key {
   -webkit-box-orient: vertical;
-  background-color: rgba(24, 24, 24, 0.9);
   border: 2px solid #7f7f7f;
   border-radius: 4px;
   color: rgb(151, 151, 151);
@@ -70,13 +69,19 @@ body {
   position: absolute;
 }
 
+.keyboard-overlay-key-background {
+  background-color: rgba(24, 24, 24, 0.9);
+}
+
 .keyboard-overlay-key.is-shortcut {
-  background: -webkit-linear-gradient(rgba(61, 61, 61, 0.8),
-                                      rgba(27, 27, 27, 0.8));
   border-color: #fafafa;
   color: #9e9e9e;
 }
 
+.keyboard-overlay-shortcut-key-background {
+  background: linear-gradient(rgba(61, 61, 61, 0.8), rgba(27, 27, 27, 0.8));
+}
+
 .keyboard-overlay-key.is-shortcut.modifier-shift {
   border-color: rgb(97, 186, 100);
 }