Adobe released yesterday Acrobat Reader DC 15.023.20053 that included fixes for 29 security issues. Along with the security fixes, this update package also silently installs the Adobe Acrobat extension into the user's Chrome web browser.
If the package fails on Windows 8.1 or earlier, this might be due to the installation of kb2919355 (which is a dependency of this package) if your system is not up-to-date. This KB requires a reboot of the system before the adobereader package installs successfully. 2b1af7f3a8