[MD Bookmarks] Scroll list to top on folder change.

chrome/browser/resources/md_bookmarks/list.js

Index: chrome/browser/resources/md_bookmarks/list.js
diff --git a/chrome/browser/resources/md_bookmarks/list.js b/chrome/browser/resources/md_bookmarks/list.js
index cb0bdb9a9e8b464876d9698c91f35c2b7826c86e..a4a5f15bec741b036f67bc545b3bd4fcb620d46c 100644
--- a/chrome/browser/resources/md_bookmarks/list.js
+++ b/chrome/browser/resources/md_bookmarks/list.js
@@ -32,7 +32,16 @@ Polymer({
     },
 
     /** @private */
-    searchTerm_: String,
+    searchTerm_: {
+      type: String,
+      observer: 'onDisplayedListSourceChange_',
+    },
+
+    /** @private */
+    selectedFolder_: {
+      type: String,
+      observer: 'onDisplayedListSourceChange_',
+    },
   },
 
   listeners: {
@@ -49,6 +58,9 @@ Polymer({
     this.watch('searchTerm_', function(state) {
       return state.search.term;
     });
+    this.watch('selectedFolder_', function(state) {
+      return state.selectedFolder;
+    });
     this.updateFromStore();
 
     this.$.bookmarksCard.addEventListener(
@@ -90,6 +102,11 @@ Polymer({
     }
   },
 
+  /** @private */
+  onDisplayedListSourceChange_: function() {
+    this.scrollTop = 0;
+  },
+
   /** @private */
   emptyListMessage_: function() {
     var emptyListMessage = this.searchTerm_ ? 'noSearchResults' : 'emptyList';