Fix tts engine links

- window.open's second argument is the context; in this case, we don't have one.
- Polymer recommends wrapping a paper-button with an anchor when treating the button like a link.
- s/options_page/optionsPage

Test: load an engine with a options page. Ensure it shows up and opens that page when clicked.
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I4210d6c306e2392841fdd9b9fb90ea1ab5c6ffb3
Reviewed-on: https://chromium-review.googlesource.com/1040679Reviewed-by: Hector Carmona <hcarmona@chromium.org>
Reviewed-by: Katie Dektar <katie@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556277}

chrome/browser/resources/settings/a11y_page/tts_subpage.html

@@ -91,11 +91,14 @@
         <div id="extension_name_[[index]]" class="start">
           [[extension.name]]
         </div>
-        <paper-button on-click="onManageTtsEngineSettingsClick_"
-            aria-describedby="extension_name_[[index]]"
-            hidden="[[!extension.options_page]]">
-          $i18n{settings}
-        </paper-button>
+        <a href="[[extension.optionsPage]]"
+            tabindex=-1
+            target="_blank"
+            hidden="[[!extension.optionsPage]]">
+          <paper-button aria-describedby="extension_name_[[index]]">
+            $i18n{settings}
+          </paper-button>
+        </a>
       </div>
     </template>
     <div class="settings-box block continuation">

chrome/browser/resources/settings/a11y_page/tts_subpage.js

@@ -110,14 +110,6 @@ Polymer({
     });
   },
 
-  /**
-   * Function to navigate to the options page for an extension.
-   * @param {TtsHandlerExtension} engine
-   * @private */
-  onManageTtsEngineSettingsClick_: function(engine) {
-    window.open(engine.optionsPage, '_blank');
-  },
-
   /** @private */
   onPreviewTtsClick_: function() {
     let utter = new window.SpeechSynthesisUtterance();