What lurks behind these Gmail/GTalk permissions? I just stumbled upon some permissions which sound clear at first sight (noticed them already quite a while ago, just decided to dig deeper right now). Thinking about possible implications, I'd really like to know what features/data they give access to, as this might get quite personal/sensitive:


com.google.android.gm.permission.READ_GMAIL: often the reason given is "to access attachments" (such as PDF files to be opened with a PDF reader). But is that all? Or could an app equipped with this permission read the entire mail?
com.google.android.gm.permission.WRITE_GMAIL: could an app with this permission write and send mails on my behalf? Or even delete existing mails (including the "written-and-sent one", to hide its activities)?
com.google.android.gm.permission.READ_CONTENT_PROVIDER: one app describes its use as "read Gmail labels and get unread count". Another one writes "Used to update the unread email count on your lockscreen. Email content is not sent to our servers." Which suggests this permission can be used to access the entire mail content. And other contents?
In some source code I found the comment Permission required to access android.content.ContentProvider, which suggests a lot of content getting accessible this way if it means THE content provider, including contacts and calendars. Not being an Android dev, I cannot really tell without being told first.
google.android.gtalkservice.permission.GTALK_SERVICE: Yes, please?


I've "googled" them all (the above is already the result of my research). And of course I started with my favorite sources when it comes to permissions:


the permission reference at Android Developers
explained permissions at AndroidForums.COM
some framework source code at Github
more framework source code at Android Source
our very own reference at What do the permissions that applications require mean?


But the above is all I could come up with. Can somebody shed some more light on those? From a user's perspective, what can be accessed with those permissions, and what are the privacy implications? A "good cop/bad cop" play would be appreciated, naturally :)
More than one year later, and no answer here. I've done some research myself – and though there was not much found, I'll share what I've got so far:


com.google.android.gm.permission.READ_GMAIL: A good guess is this targets the mail content. Protection level switched from "dangerous" to "signature" about the time Gingerbread was released (with Gmail 2.3.5), see Android Census – so it's not available to third-party apps (anymore) – and thus not relevant unless we're talking about system apps.
com.google.android.gm.permission.WRITE_GMAIL: Permits an app to change your E-Mails in Google Mail. This includes sending and deleting.Assigned protection level differs between devices (dangerous/signature), so no general say on whether it affects non-system apps.
com.google.android.gm.permission.READ_CONTENT_PROVIDER: This is primarily for access to information on Mails in Gmail. Developers can use this content provider to display label information to the user.Protection level is "dangerous" – so unless that's changed meanwhile, this one definitely affects user-apps.
google.android.gtalkservice.permission.GTALK_SERVICE: I couldn´t find any documentation on this permission, which is connected to Google Talk resp. Google Hangouts.The protection level assigned seems to differ between devices – so again no clear rule here.