[CORE-1951] Add initial_referrer for every session

[msiddiq-branch]

Reference

CORE-1951 -- Collect initial_referrer from Android SDK.

Description

Added initial_referrer-> EXTRA_REFERRER to every OPEN/INSTALL session request.

Testing Instructions

Step 1: Click on branch link from sms app
Step 2: INSTALL/OPEN the app
Step 3: Under logcat observe that v1/install or v1/open has new param called initial_referrer with the package name of referring app which is SMS app here(android-app://com.google.android.apps.messaging)
Step 4: Without click on any link try opening the app in which case EXTRA_REFERRER will be null and will have default value bnc_no_value

Risk Assessment [LOW]

• I, the PR creator, have tested — integration, unit, or otherwise — this code.

Reviewer Checklist (To be checked off by the reviewer only)

• JIRA Ticket is referenced in PR title.
• Correctness & Style
  • Conforms to AOSP Style Guides
  • Mission critical pieces are documented in code and out of code as needed.
• Unit Tests reviewed and test issue sufficiently.
• Functionality was reviewed in QA independently by another engineer on the team.

[aaaronlopez]

@bklastaitis-branch @jdee @echo-branch Can you take a pass on this PR if you guys have time too? Thanks

[jdee]

Looks good, but could use a little clean-up.

[bklastaitis-branch]

@msiddiq-branch I'm assuming Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1 is OK by product? Or if not, is there any other way we can achieve the same functionality on the lower API levels?

Also, nitpick: let's use !TextUtils.isEmpty(activity.getReferrer()) instead of activity.getReferrer() != null, that way we'll capture empty strings as well as nulls.

Finally, this reminded me of a recent inquiry about the intent keys that Branch uses, this would have potentially gone under the radar because the intent keys we use to extract data via getReferrer() are not listed among Defines.IntentKeys.. so maybe we could add a comment ssomewhere e inside Defines.IntentKeys that says:

    // The below intent keys are also used to extract data from the intent (via Activity.getReferrer())
    // public static final String EXTRA_REFERRER = "android.intent.extra.REFERRER";
    // public static final String EXTRA_REFERRER_NAME = "android.intent.extra.REFERRER_NAME";

[msiddiq-branch]

@bklastaitis-branch Currently since our SDK supports minimum SDK as 21 I believe we need to pass this value from API 21. I will figure out a method to fetch this value in the lower API version. Currently, getReferrer is supported from Api 22. cc @aaaronlopez

[msiddiq-branch]

@bklastaitis-branch I have replaced Activity.getReferrer with Activitycompat.getReferrer but still we are able to get referrer info only from API version 22 ideally this should have worked. I have been testing this on an emulator I'm not sure if that could be the reason. As per the code from google the implementation for version lower than 22 would something as mentioned here and Activitycompat.getReferrer has the same implementation.
Also while debugging in the lower version I see that intent does not have extra info being passed when app is launched from link/launcher which looks like we are not getting referrer info from API version lower than 22

@aaaronlopez Are we okay to have this supported from API 22?

[aaaronlopez]

min api support being LOLLIPOP_MR1 is fine by me for this API 👍

[msiddiq-branch]

Thanks for confirming Aaron.

[aaaronlopez]

👍

@bklastaitis-branch if you have time for one final pass, please do!

changes implemented

[bklastaitis-branch]

LGTM!