Unified Login: Track events for WPcom login flow

[AmandaRiu]

Closes #2721 by adding the final tracks events for the WPcom login flow. This includes:

• Setting the flow to wordpress_com when the Continue with WordPress.com button is clicked.
• Track events for google login
• Persisting source and flow track state to AppPrefs so if the user closes the app on the store picker screen and returns later we can restore those two values.

Note: Track events for magic link and password were already added in a previous PR

Sample Track events

Flow: Wordpress.com + magic link

Tracked: unified_login_step, Properties: {"source":"default","flow":"prologue","step":"prologue"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"prologue","step":"prologue","click":"continue_with_wordpress_com"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"wordpress_com","step":"enter_email_address"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"wordpress_com","step":"start","click":"submit"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"start"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_magic_link","step":"start","click":"request_magic_link"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"magic_link_requested"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"email_opened"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_magic_link","step":"email_opened","click":"open_email_client"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_magic_link","step":"email_opened","click":"request_magic_link"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"magic_link_requested"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"email_opened"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_magic_link","step":"email_opened","click":"open_email_client"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"success"}

Flow: WordPress.com + password

Tracked: unified_login_step, Properties: {"source":"default","flow":"prologue","step":"prologue"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"prologue","step":"prologue","click":"continue_with_wordpress_com"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"wordpress_com","step":"enter_email_address"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"wordpress_com","step":"start","click":"submit"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_magic_link","step":"start"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_magic_link","step":"start","click":"login_with_password"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_password","step":"start"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"login_password","step":"start","click":"submit"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"login_password","step":"success"}

Flow: Google Login (2FA)

Tracked: unified_login_step, Properties: {"source":"default","flow":"prologue","step":"prologue"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"prologue","step":"prologue","click":"continue_with_wordpress_com"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"wordpress_com","step":"enter_email_address"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"google_login","step":"start"}
Tracked: unified_login_interaction, Properties: {"source":"default","flow":"wordpress_com","step":"start","click":"submit_2fa_code"}
Tracked: unified_login_step, Properties: {"source":"default","flow":"wordpress_com","step":"success"}

To Test

• Test logging in with WordPress.com flow w/ magic link flow
• Test logging in with WordPress.com flow w/ password flow
• Test logging in with WordPress.com flow w/ google login
• Test closing the app on the store picker screen and restoring the app. The source and flow should be reinstated and the success event tracked successfully. For example:

Tracked: unified_login_step, Properties: {"source":"default","flow":"wordpress_com","step":"success"}

Update release notes:

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-woocommerce]

	Fails
🚫	Danger failed to run /app/danger-0.sngnz6j2ui8.ts.

Messages

📖

This PR contains changes in the subtree libs/login/. It is your responsibility to ensure these changes are merged back into wordpress-mobile/WordPress-Login-Flow-Android. Follow these handy steps! WARNING: Make sure your git version is 2.19.x or lower - there is currently a bug in later versions that will corrupt the subtree history! cd woocommerce-android git checkout issue/2721-tracks-2 git subtree push --prefix=libs/login/ https://github.com/wordpress-mobile/WordPress-Login-Flow-Android.git merge/woocommerce-android/2843 Browse to https://github.com/wordpress-mobile/WordPress-Login-Flow-Android/pull/new/merge/woocommerce-android/2843 and open a new PR.

Error TypeError

Cannot read property 'diff' of null
TypeError: Cannot read property 'diff' of null
    at checkCommitDiffs (/app/danger-0.sngnz6j2ui8.ts:43:49)
    at process._tickCallback (internal/process/next_tick.js:68:7)

Dangerfile

38|         if (git === undefined) {
39|             console.log("About to crash due to an error")
40|             console.log("File:", thisFile)
41|             console.log("Danger Object: ", danger)
42| 
---------------------------------------------------^
43|             if (danger !== undefined) {
44|                 console.log("Danger is no longer defined")
45|             }
46|             else {

Generated by 🚫 dangerJS

[peril-woocommerce]

You can test the changes on this Pull Request by downloading the APK here.

[nbradbury]

Should we track the failure even if the message is null? No message will be logged, but a Stat.UNIFIED_LOGIN_FAILURE event will still occur, which we probably want to capture.

[AmandaRiu]

Normally, yes, but the way this is used in the login library is to clear the error on a text field, which means it occurs constantly while typing in a text field.

[AmandaRiu]

Thanks for the review @nbradbury! Addressed code comments and ready for another round 👍

[nbradbury]