MD Extensions: navigate to list view when searching.

Bug: 769572
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I87beab786bcc3644290ff555994af980f3dbe59d
Reviewed-on: https://chromium-review.googlesource.com/723610Reviewed-by: Dave Schuyler <dschuyler@chromium.org>
Commit-Queue: Scott Chen <scottchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510214}

chrome/browser/resources/md_extensions/manager.js

@@ -199,6 +199,8 @@ cr.define('extensions', function() {
      * @private
      */
     onFilterChanged_: function(event) {
+      if (this.currentPage_.page !== Page.LIST)
+        extensions.navigation.navigateTo({page: Page.LIST});
       this.filter = /** @type {string} */ (event.detail);
     },