MD Settings: Fix iron-list losing focus when items change.

third_party/polymer/v1_0/chromium.patch

Index: third_party/polymer/v1_0/chromium.patch
diff --git a/third_party/polymer/v1_0/chromium.patch b/third_party/polymer/v1_0/chromium.patch
index 8b99b23f099dfaa63080fe6a058cbaf9e4286782..f17d16a458e2ae11f02a4f09971977e953e2195e 100644
--- a/third_party/polymer/v1_0/chromium.patch
+++ b/third_party/polymer/v1_0/chromium.patch
@@ -24,3 +24,70 @@ index 78a2a9ec621c..8b776dd790ea 100644
      },
  
      _ariaDescribedByChanged: function(ariaDescribedBy) {
+diff --git a/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js b/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
+index 9e9ec02f9c9c..eb492f1e3f8a 100644
+--- a/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
++++ b/third_party/polymer/v1_0/components-chromium/iron-list/iron-list-extracted.js
+@@ -126,6 +126,14 @@
+       scrollOffset: {
+         type: Number,
+         value: 0
++      },
++
++      /**
++       * If set to true, focus on an element will be preserved after rerender.
++       */
++      preserveFocus: {
++        type: Boolean,
++        value: false
+       }
+     },
+ 
+@@ -894,6 +902,15 @@
+      * to `items`, splices or updates to a single item.
+      */
+     _itemsChanged: function(change) {
++      var rendering = ['items', 'items.splices'].includes(change.path);
++      var lastFocusedIndex, focusedElement;
++      if (rendering && this.preserveFocus) {
++        lastFocusedIndex = this._focusedIndex;
++        focusedElement = this.querySelector('* /deep/ *:focus');
++      }
++
++      var preservingFocus = rendering && this.preserveFocus && focusedElement;
++
+       if (change.path === 'items') {
+         this._virtualStart = 0;
+         this._physicalTop = 0;
+@@ -906,12 +923,11 @@
+         this._physicalItems = this._physicalItems || [];
+         this._physicalSizes = this._physicalSizes || [];
+         this._physicalStart = 0;
+-        if (this._scrollTop > this._scrollOffset) {
++        if (this._scrollTop > this._scrollOffset && !preservingFocus) {
+           this._resetScrollPosition(0);
+         }
+         this._removeFocusedItem();
+         this._debounceTemplate(this._render);
+-
+       } else if (change.path === 'items.splices') {
+         this._adjustVirtualIndex(change.value.indexSplices);
+         this._virtualCount = this.items ? this.items.length : 0;
+@@ -920,6 +936,17 @@
+       } else {
+         this._forwardItemPath(change.path.split('.').slice(1).join('.'), change.value);
+       }
++
++      // If the list was in focus when updated, preserve the focus on item.
++      if (preservingFocus) {
++        Polymer.dom.flush();
++        focusedElement.blur(); // paper- elements breaks when focused twice.
++        this._focusPhysicalItem(
++            Math.min(this.items.length - 1, lastFocusedIndex));
++        if (!this._isIndexVisible(this._focusedIndex)) {
++          this.scrollToIndex(this._focusedIndex);
++        }
++      }
+     },
+ 
+     /**