Earlier this week Microsoft released Windows 10 19H1 Build 18237 to Windows Insiders who opted into the Skip Ahead ring for the next feature update of the operating system. This seventh feature update, using the code name 19H1, will be under development until the March/April 2019 time frame when it should become generally available.
The connection between the Windows 10 desktop and the Android device being used for messaging or accessing these images is the Microsoft Apps app. Using this app you would authorize the Your Phone app on your Windows 10 device to access your Android device for that access. The Microsoft Apps app has been around for a while as a way to discover apps built by Microsoft for the Android platform with the Your Phone capabilities added recently.
Microsoft has now decided to re-brand the Microsoft Apps app to the Your Phone Companion app in order to better communicate the relationship between the two apps. As you will see in the screenshots below, the app does retain its listing of Microsoft apps to continue helping with the discovery of those apps for your Android device.
This re-branded app has been rolling out since the change was announced with the release of Windows 10 19H1 Build 18237 and is apparently continuing. Myself and others are now starting to see the update on our devices as of this morning.
The Your Phone app currently works on Skip Ahead builds for Windows 10 19H1, Fast and Slow Ring builds for Windows 10 Redstone 5 and Windows 10 production devices that are in the Release Preview Ring for app and driver updates. Your Phone capabilities are only available to Android users right now but it is expected to arrive for iOS devices sometime in the future. However, the Your Phone capabilities tied to an iOS device are not expected to be as robust in comparison due to limitations imposed by Apple for these types of interactions.
Your Phone Companion App Screenshots on Android