Too Long; Didn't Read
Every app in Android has it's own set of requested permissions so how are these permissions assigned to the app? In Android, app is nothing but a process. Permissions are enforced at various layers in Android. The package manager maintains a central database of installed packages, both preinstalled and user-installed, with information about the install path, version, signing certificate, and assigned permissions of each package, as well as a list of all permissions defined on a device. When user press OK button, Package Manager call method named "installPackage"