Settings: workaround iron-list rendering issue by clearing sites on route change

Bug: 851431
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ib81a7c7bc9cd2177919702c078b140e6a0b39281
Reviewed-on: https://chromium-review.googlesource.com/1096351
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Reviewed-by: Scott Chen <scottchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568258}

chrome/browser/resources/settings/site_settings/BUILD.gn

@@ -138,6 +138,7 @@ js_library("site_data_details_subpage") {
   deps = [
     ":local_data_browser_proxy",
     "..:route",
+    "//third_party/polymer/v1_0/components-chromium/iron-list:iron-list-extracted",
     "//ui/webui/resources/js:cr",
     "//ui/webui/resources/js:web_ui_listener_behavior",
   ]

chrome/browser/resources/settings/site_settings/site_data.js

@@ -103,6 +103,11 @@ Polymer({
         this, currentRoute);
     if (currentRoute == settings.routes.SITE_SETTINGS_SITE_DATA) {
       this.isLoading_ = true;
+      // Needed to fix iron-list rendering issue. The list will not render
+      // correctly until a scroll occurs.
+      // See https://crbug.com/853906.
+      const ironList = /** @type {!IronListElement} */ (this.$$('iron-list'));
+      ironList.scrollToIndex(0);
       this.browserProxy_.reloadCookies().then(this.updateSiteList_.bind(this));
     }
   },