Hotword Audio Verification App: Adds hotwording assets and basic opt-in flow.

chrome/browser/resources/hotword_audio_verification/event_page.js

Index: chrome/browser/resources/hotword_audio_verification/event_page.js
diff --git a/chrome/browser/resources/hotword_audio_verification/event_page.js b/chrome/browser/resources/hotword_audio_verification/event_page.js
index c734c78f4d99dd0c3dae239443cbad09d69dcb94..41272010025ee3aad4fa605abd929a9fe88ab3ae 100644
--- a/chrome/browser/resources/hotword_audio_verification/event_page.js
+++ b/chrome/browser/resources/hotword_audio_verification/event_page.js
@@ -7,8 +7,10 @@ chrome.app.runtime.onLaunched.addListener(function() {
     'frame': 'none',
     'resizable': false,
     'bounds': {
-      'width': 710,
-      'height': 535
+      'width': 800,
+      'height': 600
     }
+  }, function(appWindow) {
+    appWindow.contentWindow.appWindow = appWindow;
   });
 });