Adding atom for logging GrantPermissionsActivity buttons presented and pressed.

Test: make statsd_testdrive && ./out/host/linux-x86/bin/statsd_testdrive -p com.google.android.permissioncontroller 213
Bug:133401502
Bug:134581123
Change-Id: I4c74d590266f89b192605be6f94d038bc2e1bd5a