Update SiteCreationService from latest AutoForeground

[hypest]

Bring over to SiteCreationService the latest AutoForeground updates from develop. While at it, unify and remove code duplication by moving common functionality inside the AutoForeground class.

To test #1:

• Make sure that the testplan in Perform the WPCOM email+password login in the background #6878 (comment) still works OK

To test #2:

• Make sure that the testplan in Site creation service #6825 (comment) also works OK

[nbradbury]

Unrelated to this PR, but is the wording in this notification set in stone? I think we can just say "Logging in..." and drop the "Please wait while logging in."

[hypest]

Thanks for picking this up for review @nbradbury !

The notification copy is planned to be updated later, to match the design as shown in #6929. Is it OK with you to address it at that point?

[nbradbury]

The notification copy is planned to be updated later, to match the design as shown in #6929. Is it OK with you to address it at that point?

Yep, that's fine.

[nbradbury]

Code-wise this looks good to me, but I've asked @mzorz to take a look since he tackled the original PR.

[mzorz]

Hi @hypest - the code looks good to me as well 👍 (except for the strings.xml conflict that has just appeared with develop - check that)

While testing, had the good luck to make it crash though, this is what I did:

1. following the steps in Site creation service #6825 (comment):
2. after tapping "+" and sending the app to the background, I can see the foreground notification appear. My phone was locked in portrait, so I decided to unlock it and give some orientation changes a shot. It was then when the crash happened:

12-14 09:09:22.696 16007-16007/org.wordpress.android D/AndroidRuntime: Shutting down VM
12-14 09:09:22.699 16007-16007/org.wordpress.android E/AndroidRuntime: FATAL EXCEPTION: main
                                                                       Process: org.wordpress.android, PID: 16007
                                                                       java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.wordpress.android.fluxc.model.ThemeModel.getThemeId()' on a null object reference
                                                                           at org.wordpress.android.ui.accounts.signup.SiteCreationService.activateTheme(SiteCreationService.java:214)
                                                                           at org.wordpress.android.ui.accounts.signup.SiteCreationService.access$700(SiteCreationService.java:36)
                                                                           at org.wordpress.android.ui.accounts.signup.SiteCreationService$3.onSettingsSaved(SiteCreationService.java:294)
                                                                           at org.wordpress.android.ui.prefs.SiteSettingsInterface$5.run(SiteSettingsInterface.java:997)
                                                                           at android.os.Handler.handleCallback(Handler.java:789)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:98)
                                                                           at android.os.Looper.loop(Looper.java:164)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
12-14 09:09:22.705 914-5742/? W/ActivityManager:   Force finishing activity org.wordpress.android/.ui.accounts.NewBlogActivity

[hypest]

Thanks for the pass @mzorz ! I've added a commit to help with the strings.xml conflict but unfortunately, I'm not able to replicate the crash. Do you have some more specific steps to reproduce?

[mzorz]

I'm not able to replicate the crash. Do you have some more specific steps to reproduce?

Not able to reproduce myself. Probably a combination of factors, and probably not strictly related to the PR itself.

Let's merge once Travis passes 👍

[mzorz]