Rather than created a nested URI with an inner "moz-safe-about" URI, we should always create an nsSimpleURI. We can then use the nsIProtocolHandlerWithDynamicFlags mechanism to give different security properties to different about: URIs.

Part of the challange here is that IndexedDB's file formats ends up using the moz-safe-about scheme name. The origin of the page which uses IndexedDB, is stored in 3 places in the filesystem: * The directory name (each origin gets a separate directory). * Each directory gets a .metadata file which contain the origin and some other information. * Each IDB sqlite database contains a "database" table which has an "origin" column with the origin. Calculating this origin (correctly) grabs the innermost URI, which means that we use a moz-safe-about: scheme. However there's two pieces of good news. First off, it seems like all our origin handling for about: URIs go through the TryGetInfoForAboutURI [1] function. That means that it is quite easy to change our handling there to make sure that even though we change about: URIs to never be parsed into inner moz-safe-about URIs, we can easily act as if we did in order to avoid changing the on-disk format. Second, in bug 1195930 we're going to change the way that origins are stored on disk. So we can rather easily at the same time change how about: origins are stored. It's unclear if bug 1195930 will be fixed first, or if we'll change about: URIs first. But either way I think we should not worry about upgrading on-disk format as part of changing about: URIs. Instead we should do the conversion when writing an about: origin to disk. Updating the on-disk format fewer times is better for both performance and ability to downgrade anyway. Additionally we do have code which reads one of these origins back from disk and parses them in OriginParser::ParseOrigin [2]. It sounds like we use this to restore .metadata files using a directory name since for some reason the .metadata files sometimes gets lost. So this code would also need to get updated to convert moz-safe-about origins properly. [1] http://mxr.mozilla.org/mozilla-central/source/dom/quota/ActorsParent.cpp#4030 [2] http://mxr.mozilla.org/mozilla-central/source/dom/quota/ActorsParent.cpp#6241

Note to self: when we do this I would like to make sure that checkLoadURI and friends in caps/ still don't let non-chrome-privileged about: link to chrome-privileged about: .

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258

Bulk change to priority: https://bugzilla.mozilla.org/show_bug.cgi?id=1399258