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

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

 <!-- TODO(crbug.com/603217): Use i18n instead of string literals. Figure out
                              what i18n to use for keypad, ie, does 1 ABC make
                              sense in every scenario? -->
 
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/paper-styles.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 
 <dom-module id="pin-keyboard">
@@ skipping 107 matching lines @@
         pointer-events: none;
       }
     </style>
 
     <div id="root">
       <div id="container-constrained-width">
         <div class="row">
           <input id="pin-input" type="number" placeholder="Enter PIN"
                  value="{{value::input}}"
                  on-keydown="onInputKeyDown_"></input>
-          <paper-button class="digit-button first-row submit-button"
+          <paper-button class="digit-button submit-button"
+                        on-focus="onButtonFocus_"
+                        on-keydown="onButtonKeyDown_"
                         on-tap="firePinSubmitEvent_">
             <div class$="icon-container [[computeSubmitClass_(value)]]">
                 <iron-icon class="icon" icon="icons:forward"><iron-icon>
             </div>
           </paper-button>
         </div>
 
         <div class="row keyboard">
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="1">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="1">
             <inner-text>1</inner-text>
           </paper-button>
-          <paper-button class="digit-button center-button" on-tap="onNumberTap_"
-                        value="2">
+          <paper-button class="digit-button center-button"
+                        on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="2">
             <inner-text>2</inner-text>
           </paper-button>
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="3">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="3">
             <inner-text>3</inner-text>
           </paper-button>
         </div>
         <div class="row keyboard">
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="4">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="4">
             <inner-text>4</inner-text>
           </paper-button>
-          <paper-button class="digit-button center-button" on-tap="onNumberTap_"
-                        value="5">
+          <paper-button class="digit-button center-button"
+                        on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="5">
             <inner-text>5</inner-text>
           </paper-button>
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="6">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="6">
             <inner-text>6</inner-text>
           </paper-button>
         </div>
         <div class="row keyboard">
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="7">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="7">
             <inner-text>7</inner-text>
           </paper-button>
-          <paper-button class="digit-button center-button" on-tap="onNumberTap_"
-                        value="8">
+          <paper-button class="digit-button center-button"
+                        on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="8">
             <inner-text>8</inner-text>
           </paper-button>
-          <paper-button class="digit-button" on-tap="onNumberTap_" value="9">
+          <paper-button class="digit-button" on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="9">
             <inner-text>9</inner-text>
           </paper-button>
         </div>
         <div class="row keyboard">
           <div class="digit-button"></div>
-          <paper-button class="digit-button center-button" on-tap="onNumberTap_"
-                        value="0">
+          <paper-button class="digit-button center-button"
+                        on-keyup="onButtonKeyUp_"
+                        on-tap="onNumberTap_" value="1">
             <inner-text>0</inner-text>
           </paper-button>
-          <paper-button class="digit-button clear-button" on-tap="onPinClear_">
+          <paper-button class="digit-button clear-button"
+                        on-keyup="onButtonKeyUp_"
+                        on-tap="onPinClear_">
             <div class="icon-container">
               <iron-icon class="icon" icon="icons:clear"><iron-icon>
             </div>
             <inner-text class="icon-subheading">Clear</inner-text>
           </paper-button>
         </div>
       </div>
     </div>
   </template>
   <script src="pin_keyboard.js"></script>
 </dom-module>