Add notifications on build failures (#1923)

Author: kevmoo

.travis.yml

@@ -7,6 +7,9 @@ language: dart
 dart:
   - dev
 
+after_failure:
+  - tool/report_failure.sh
+
 # Only building master means that we don't run two builds for each pull request.
 branches:
   only: [master]

dev/tool/travis/prefix.yaml

@@ -7,6 +7,9 @@ language: dart
 dart:
   - dev
 
+after_failure:
+  - tool/report_failure.sh
+
 # Only building master means that we don't run two builds for each pull request.
 branches:
   only: [master]

tool/report_failure.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+if [ "$TRAVIS_EVENT_TYPE" != "pull_request" ] && [ "$TRAVIS_ALLOW_FAILURE" != "true" ]; then
+  curl -H "Content-Type: application/json" -X POST -d \
+    "{'text':'Build failed! ${TRAVIS_BUILD_WEB_URL}'}" \
+    "${CHAT_HOOK_URI}"
+fi