Graphic Styles are files that allow you to quickly switch between appearances. I made some for drop shadows, long shadows, a finish, and shadow for th entire icon. The vanilla drop shadows are per Google's spec sheet, everything else is a derivative that I use.
For you styles like the drop shadows, you'll need to use alt-click instead of click so you don't replace existing styles. This happens because it's changing the fill of your object. It still does this when the styles don't have fills so I color coordinated them.
To use one of these files, rename it to something you can remember, then move it to a directory following the following pattern:
C:\Users\USER\AppData\Roaming\Adobe\Adobe Illustrator VERSION Settings\LANG\BIT\Graphic Styles
Replacing USER with your user, VERSION with AI's version number (CC 2014 = 18, CC 2015 = 19), LANG with your language and region (en_US), and BIT with either x86 or x64.
The directory for my computer looked like this:
C:\Users\Daniel\AppData\Roaming\Adobe\Adobe Illustrator 19 Settings\en_US\x64\Graphic Styles
My name is Daniel, I use CC 2015 (19), on 64 bit in the US.