One of the headline features of Android 4.4 is a revamped home screen and app launcher. The icons are bigger, there is more transparency, and the app drawer makes better use of the screen real estate. It's also heavily integrated with Google Search and Google Now, although you might not see it at the surface level. Sure, there's the usual search bar widget and a swipe to the left will open the full Google Search app, but the integration goes much deeper than that. While developing KitKat, Google made a very interesting decision: rather than graft a few new search UI pieces onto the home screen, Google threw the existing home app in the trash and turned all home screen functionality over to the Google Search app.
Everything you see here is being drawn by Google Search.
That's right, Google Search isn't just integrated into the home screen, it is the home screen. Everything you see on the home screen—the wallpaper, the icons, the widgets, and the app drawer—are all drawn by the Google Search app. "GoogleHome.apk" still exists, but it is an empty shell that forwards everything to the search app.
If you need proof of this, the picture below shows the layout files for the Android 4.3 launcher and the 4.4 Google Search app. Layout files do exactly what you think they do: they determine what goes where in an Android app. As the image shows, the layout files from the 4.3 launcher have all migrated over to the Google Search app. All the necessary assets and image files have made the jump, too. I would show the GoogleHome.apk layout files for comparison, but there aren't any. The launcher has been gutted and is now just a helper app that registers Google Search as the home screen. In fact, if you install GoogleHome.apk without the 4.4 Search app, it won't work at all. It just displays a message saying it requires the Google Search app to function.
Google has adopted the Facebook Home strategy. Facebook took its normal Android app and grafted an app launcher onto it—it replaced the Android home screen with something that revolved around Facebook. The wallpaper became images and status updates from your friends, and Facebook notifications were given top billing. Everything was designed to get you to use Facebook as much as possible. With KitKat, Google is working toward a similar idea. Google took its search app and gave it wallpapers, a home screen, and an app drawer, and now it's the first thing you see when you unlock a Nexus 5.
If Google just wanted to include a few new search pieces into the existing standalone home app, it could have easily done that. The search bar has traditionally been a widget, and there is even a widget that displays Google Now information. Both of those could have been expanded and made more configurable with a few tweaks to Android's widget framework, but instead of doing that, Google chose to make its Search app the primary interface. While Facebook certainly went further down the integration road than Google, the two companies are now clearly headed down the same path. Google Now cards are currently relegated to the left-most home screen, but it's not hard to imagine a future where particularly relevant cards start popping up on the main screen. After all, since Google Search is the home screen, Google Now cards are constantly in memory.
And yes, for those wondering, this means Google Home (more accurately, Google Search Home) will be in the Play Store. Google Home is the Google Search app, which is already in the Play Store, it's just an old version. Soon, you'll hit the update button and have 99 percent of the code for Google Home. Google Home doesn't even require KitKat; I've got it running on my Jelly Bean-equipped Nexus 4 right now.
Google App Indexing.
This isn't the only in-road Google Search has made into KitKat, either. The dialer and incoming call screen now automatically perform Google searches for phone number information (and will display Google Ads), and Google has just launched "App Indexing," a way to directly open a search result in the appropriate app from Google Search.
[Update: Google has gotten in touch with us, and they say they are not working on ads in the Dialer.]
If Google was going to stop here, there is no way it would need to merge Google Search and the Launcher into a single app. Android has begun a slow, gradual transformation into a Google Now device. Just like Facebook, Google wants to change the way you use your phone from an app-centric device to a device that revolves around its core product, but unlike Facebook, Google has the install base and clout with OEMs to make it happen. Remember, if OEMs want to ship any Google Apps, they need to ship allthe Google apps, so Google Home will most likely be included on every Android device. It won't necessarily be enabled by default on something like a Samsung device, but that's nothing some light badgering in the Search app won't fix ("For a better search experience, enable Google Home!"). Expect to see much more Google Now integration in the future.