According to the mechanism of Android M, default permission setting of Apps is disable when it's undergoing the installation process , and system will not require user to activate the related permission.(e.g. Camara, Contacts..)
Therefore, a window would pop-up to require the permission while using some related function after you installed the app. For example, permission windows pop up while opening the camera and taking photo. You need to tap " Grant Permission " to allow device such as camera / microphone to activate its function.
How to check the permission status of APPs?
1. Tap " Settings " > " Apps "
2. Choose the App information. For example " Camera " and tap " Permissions "
3. From the permission list, you can slide to turn on/off the permission of the function which is related to camera.
