[Hotword] Putting preferences under search for hotword service. Putting behind a flag.

chrome/browser/resources/options/browser_options.js

Index: chrome/browser/resources/options/browser_options.js
diff --git a/chrome/browser/resources/options/browser_options.js b/chrome/browser/resources/options/browser_options.js
index c0346e3c965a4c056335338bc7c9ff0e85941f5a..0871c7bbb9a066f7954a4ea202f66e930ff6a4ee 100644
--- a/chrome/browser/resources/options/browser_options.js
+++ b/chrome/browser/resources/options/browser_options.js
@@ -128,6 +128,10 @@ cr.define('options', function() {
         OptionsPage.navigateToPage('homePageOverlay');
       };
 
+      chrome.send('requestHotwordAvailabile');

[James Hawkins, 2014/01/14 00:53:50]

It's not clear how this call is tied to the added listener a line below.  For
example, what happens if (hypothetically) this browser call completes
synchronously?

[rpetterson, 2014/01/14 21:54:17]

Good point. I've swapped the order of them. Now, when the
"requestHotwordAvailable" message is sent, it should already be listening for
the reply.

+      Preferences.getInstance().addEventListener('hotword.search_enabled',
+          this.onHotwordSearchPrefChanged_.bind(this));
+
       if ($('set-wallpaper')) {
         $('set-wallpaper').onclick = function(event) {
           chrome.send('openWallpaperManager');
@@ -866,6 +870,28 @@ cr.define('options', function() {
     },
 
     /**
+     * Activates the Hotword section from the System settings page.
+     * @private
+     */
+    showHotwordSection_: function() {
+      $('hotword-search').hidden = false;
+    },
+
+    /**
+     * Event listener for the 'hotword search enabled' preference. Shows/hides
+     * the UI for updating hotword settings with animation.

[James Hawkins, 2014/01/14 00:53:50]

Do we need the 'with animation' part (in the comment and the method name)?  It
seems like an implementation details.

[rpetterson, 2014/01/14 21:54:17]

Done.

+     * @param {Event} event The preference change event.
+     */
+    onHotwordSearchPrefChanged_: function(event) {
+      var section = $('hotword-settings-section');
+      var container = $('hotword-settings-section-container');
+      if (event.value.value)

[James Hawkins, 2014/01/14 00:53:50]

Can you document what event.value.value represents?

[rpetterson, 2014/01/14 21:54:17]

Done.

+        this.showSectionWithAnimation_(section, container);
+      else
+        this.hideSectionWithAnimation_(section, container);
+    },
+
+    /**
      * Event listener for the 'homepage is NTP' preference. Updates the label
      * next to the 'Change' button.
      * @param {Event} event The preference change event.
@@ -1573,6 +1599,7 @@ cr.define('options', function() {
     'showCreateProfileError',
     'showCreateProfileSuccess',
     'showCreateProfileWarning',
+    'showHotwordSection',
     'showManagedUserImportError',
     'showManagedUserImportSuccess',
     'showMouseControls',