The Google I/O 2019 keynote was, as usual, chock full of cool announcements, and among them was mention of a lofty new goal: Project Mainline. The idea picks up where Treble left off, furthering Android's modularization and making it easier for updates to change core OS components — mitigating the effect of the big, bad Fragmentation monster.

Those core OS components can be updated sort of like apps. Remember APEX? In essence, that's a new file format for some of these Project Mainline updates sort of like APKs. Google can use both APKs and APEX files to distribute new versions of those core OS components via the Play Store, allowing them to be installed without needing a full system update — though it isn't immediately clear if they'll be updated in the background or if they'll be manageable by users like apps are.

Unlike what Google said at its Keynote, we're told you will still need to reboot for at least some of them to take effect, but it's still better than waiting on habitually slow OEMs to fix security problems.

Components that can be updated in Android Q via Project Mainline will include:

  • Security: Media Codecs, Media Framework Components, DNS Resolver, Conscrypt
  • Privacy: Documents UI, Permission Controller, ExtServices
  • Consistency: Timezone data, ANGLE (developers opt-in), Module Metadata, Networking components, Captive Portal Login, Network Permission Configuration

With how many media framework-related security problems Android has had over the years, it's good to see it included.

Furthermore, Project Mainline will likely need OEMs to build support for it into their software, and they'll have to accept handing off the responsibility for more of these core Android components to Google. Presumably, Google will place pressure on them to do this via things like GMS certification requirements, though that's speculative.

Like all of Google's "Project" codenames for Android, this one sounds lofty and it's not at all clear how smoothly it will go. Whether or not this works remains to be seen, but it's a step in the right direction for Android.

Earlier today, Google released more information about precisely how Project Mainline works. We have updated our coverage with a more detailed explanation.