Suppress the exception thrown when responding to message with no response callback.

chrome/test/data/extensions/hotword/manifest.json

Index: chrome/test/data/extensions/hotword/manifest.json
diff --git a/chrome/test/data/extensions/api_test/hotword_private/isAvailable/manifest.json b/chrome/test/data/extensions/hotword/manifest.json
similarity index 71%
copy from chrome/test/data/extensions/api_test/hotword_private/isAvailable/manifest.json
copy to chrome/test/data/extensions/hotword/manifest.json
index 89dd7bc8ee64722fd871b8b00448f8b2a427b924..c99d6f118bdba2005a633d31ad770c964203c3d6 100644
--- a/chrome/test/data/extensions/api_test/hotword_private/isAvailable/manifest.json
+++ b/chrome/test/data/extensions/hotword/manifest.json
@@ -1,12 +1,11 @@
 {
   // chrome-extension://cpfhkdbjfdgdebcjlifoldbijinjfifp/
   "key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDCXAxIB5iu+XGtMYYJgSwMrqO+zNa3FlWeMJLOV+U1T2VL6wDU3WD9YNlioI6a6wG49AFquEbRxQwwxlvAZC1c95LBvRlnQAkEVum0KbrJ8WHTxxDEPOfITE0J1AP5j8V0WQ9jbYvUxgefIPhDPXHpdPRAxDotygTrPa33x1075wIDAQAB",
-  "name": "Hotword Private Test Extension",
+  "name": "Hotword Helper Test Extension",
   "version": "0.1",
   "manifest_version": 2,
-  "description": "Browser tests for chrome.hotword_private API",
+  "description": "Browser test for hotword helper extension",
   "background" : {
     "scripts": ["test.js"]
-  },
-  "permissions": ["hotwordPrivate"]
+  }
 }