[MD settings] merge polymer 1.0.11; hack for settings checkbox

third_party/polymer/v1_0/components-chromium/paper-checkbox/paper-checkbox-extracted.js

-
-    Polymer({
+Polymer({
       is: 'paper-checkbox',
 
       behaviors: [
         Polymer.PaperInkyFocusBehavior
       ],
 
       hostAttributes: {
         role: 'checkbox',
         'aria-checked': false,
         tabindex: 0
@@ skipping 27 matching lines @@
          * If true, the button toggles the active state with each tap or press
          * of the spacebar.
          */
         toggles: {
           type: Boolean,
           value: true,
           reflectToAttribute: true
         }
       },
 
-      ready: function() {
-        if (Polymer.dom(this).textContent == '') {
+      attached: function() {
+        var trimmedText = Polymer.dom(this).textContent.trim();
+        if (trimmedText === '') {
           this.$.checkboxLabel.hidden = true;
-        } else {
-          this.setAttribute('aria-label', Polymer.dom(this).textContent);
+        }
+        // Don't stomp over a user-set aria-label.
+        if (trimmedText !== '' && !this.getAttribute('aria-label')) {
+          this.setAttribute('aria-label', trimmedText);
         }
         this._isReady = true;
       },
 
       // button-behavior hook
       _buttonStateChanged: function() {
         if (this.disabled) {
           return;
         }
         if (this._isReady) {
@@ skipping 13 matching lines @@
         }
         return '';
       },
 
       _computeCheckmarkClass: function(checked) {
         if (!checked) {
           return 'hidden';
         }
         return '';
       }
-    })
-  
+    });