Bug 1410794 - Change some |string| occurrences in nsIPrefBranch.idl to |ACString|. r=erahm. This makes the code nicer. In particular, it removes many getter_Copies() calls. The patch also converts a lot of nsCStrings to nsAutoCString, which will avoid heap allocation in the common case. The patch also renames PREF_CopyCharPref() as PREF_GetCStringPref(), because it's actually getting a string, not a char, and that matches the existing GetCString() and GetDefaultCString() methods. Correspondingly, it also renames PREF_SetCharPref() as PREF_SetCStringPref(). The |aPrefName| arguments in nsIPrefBranch.idl remain as |string| because they almost always involve passing in C string literals, and passing "foo" is much nicer than passing NS_LITERAL_CSTRING("foo"). It's worth noting that early versions of this patch used |AUTF8String| instead of |ACString|. But it turns out that libpref stores prefs internally as Latin1. And |ACString| is compatible with Latin1 but |AUTF8String| isn't, because non-ASCII Latin1 strings are not valid UTF-8!

XPI_ROOT_APPID=$(MOZ_APP_ID)