build(aio): fix example protractor config for Travis (#21309)

Without setting the CHROME_BIN Travis will not use the correct version
of Chrome for running e2e tests.

Closes #20159

PR Close #21309

aio/tools/examples/shared/boilerplate/cli/protractor.conf.js

@@ -9,7 +9,11 @@ exports.config = {
     './e2e/**/*.e2e-spec.ts'
   ],
   capabilities: {
-    'browserName': 'chrome'
+    'browserName': 'chrome',
+    // For Travis CI only
+    chromeOptions: {
+      binary: process.env.CHROME_BIN
+    }
   },
   directConnect: true,
   baseUrl: 'http://localhost:4200/',