Pin keyboard use enter to submit when focus is not on a button.

chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js

Index: chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
diff --git a/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js b/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
index dfc111d4c5fcd7c32df8aa1e7a95762d0894bfbb..b7e6e75f75ca7873a04ba378251fee03273d7c1a 100644
--- a/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
+++ b/chrome/browser/resources/chromeos/quick_unlock/pin_keyboard.js
@@ -35,15 +35,32 @@ Polymer({
     }
   },
 
+  // The current focused element.
+  focusedElement_: undefined,
+
   /** Transfers focus to the input element. */
   focus: function() {
-    this.$$('#pin-input').focus();
+    var pinInput = this.$$('#pin-input');
+    pinInput.focus();
+    this.focusedElement_ = pinInput;
+  },
+
+  /** Called when a pin keyboard has a key pressed. */
+  onButtonKeyUp_: function(event, detail) {
+    // Only if tab has been pressed do we want change the focus.
+    if (event.target.receivedFocusFromKeyboard)
+      this.focusedElement_ = event.target;
   },
 
   /** Called when a keypad number has been tapped. */
   onNumberTap_: function(event, detail) {
     var numberValue = event.target.getAttribute('value');
     this.value += numberValue;
+
+    // If the tabbed element is clicked we want to keep the focus, otherwise
+    // transfer focus to the input.
+    if (this.focusedElement_ != event.target)

[jdufault, 2016/07/01 21:20:52]

Can we traverse the DOM to find the focused element instead of caching it? Does
document.activeElement work?

[sammiequon, 2016/07/01 22:19:14]

document.activeElement always returns the button if you tap it. But I want to
send focus back to the input if the previous focused element, so I cached it. I
think we can replace event.target with document.activeElement thought.

+      this.focus();
   },
 
   /** Fires a submit event with the current PIN value. */