Keep in sync with GoogleChrome/custom-tabs-client

[zhanghai]

https://github.com/GoogleChrome/custom-tabs-client

[zhanghai]

See:

• https://github.com/GoogleChrome/custom-tabs-client/commits/master/shared/src/main/java/org/chromium/customtabsclient/shared
• https://github.com/GoogleChrome/custom-tabs-client/commits/master/demos/src/main/java/org/chromium/customtabsdemos/CustomTabActivityHelper.java

[zhanghai]

Up-to-date as of 2016-10-25.

[NoahAndrews]

Despite the fact that there is a new commit that changes something in the shared directory, it is only an update to the custom tabs support library itself, and one of the activities in the sample. The only change to the shared directory is an extra import line.

That being said, it may be worthwhile to have this library register a BroadcastReceiver for the BrowserActions intent, and allow the user to specify a simple callback for when one of the menu options in the custom tab is selected. That commit does provide an example for handling that.