cros: Backspace button no longer changes sizes.

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/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <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/color.html">
@@ skipping 56 matching lines @@
       .bottom-row {
         margin-bottom: 6px;
       }
 
       .top-row {
         margin-top: 6px;
       }
 
       .digit-button.backspace-button {
         opacity: var(--dark-primary-opacity);
+        padding: 14px;
       }
 
       .digit-button.backspace-button:not([has-content]) {
         color: #000;
         opacity: 0.26;
-        padding: 14px;
       }
 
       .digit-button inner-text {
         color: var(--paper-blue-grey-700);
         display: flex;
         flex-direction: column;
         height: 52px;
       }
 
       #pin-input {
@@ skipping 109 matching lines @@
                              on-pointerdown="onBackspacePointerDown_"
                              on-pointerout="onBackspacePointerOut_"
                              on-pointerup="onBackspacePointerUp_">
           </paper-icon-button>
         </div>
       </div>
     </div>
   </template>
   <script src="pin_keyboard.js"></script>
 </dom-module>