The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d3665e0bb00964faf5f1f2a497225879f3da5e97

commit d3665e0bb00964faf5f1f2a497225879f3da5e97
Author: ianwen <ianwen@chromium.org>
Date: Wed Jun 15 22:30:55 2016

[Custom Tabs] Navigate to other apps if the first url is a redirect

This CL fixes two bugs.
1. Eliminate the possibility that a custom tab navigates away to an
external app while the activity is still hanging there.
2. Make external navigation possible if the first url redirects to
another one. This is because the client apps mostly lack the ability to
tell if an app can handle a shortened url. And Chrome should help them
doing so.
3. Remove an unused fieldtrial.

BUG=613667, 616825 

Review-Url: https://codereview.chromium.org/2057933002
Cr-Commit-Position: refs/heads/master@{#400029}

[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/DeferredStartupHandler.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabActivity.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnectionService.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/document/ChromeLauncherActivity.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/preferences/ChromePreferenceManager.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/java/src/org/chromium/chrome/browser/tab/TabRedirectHandler.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/chrome/android/javatests/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandlerTest.java
[modify] https://crrev.com/d3665e0bb00964faf5f1f2a497225879f3da5e97/testing/variations/fieldtrial_testing_config_android.json