Merge "Permit package downgrades on debuggable platforms." into nyc-dev

                    // predecessor. As a security measure, this is permited only if this is not a

                    // version downgrade or if the predecessor package is marked as debuggable and

                    // a downgrade is explicitly requested.

                    if (((dataOwnerPkg.applicationInfo.flags & ApplicationInfo.FLAG_DEBUGGABLE) == 0)

                            || ((installFlags & PackageManager.INSTALL_ALLOW_DOWNGRADE) == 0)) {

                    //

                    // On debuggable platform builds, downgrades are permitted even for

                    // non-debuggable packages to make testing easier. Debuggable platform builds do

                    // not offer security guarantees and thus it's OK to disable some security

                    // mechanisms to make debugging/testing easier on those builds. However, even on

                    // debuggable builds downgrades of packages are permitted only if requested via

                    // installFlags. This is because we aim to keep the behavior of debuggable

                    // platform builds as close as possible to the behavior of non-debuggable

                    // platform builds.

                    final boolean downgradeRequested =

                            (installFlags & PackageManager.INSTALL_ALLOW_DOWNGRADE) != 0;

                    final boolean packageDebuggable =

                                (dataOwnerPkg.applicationInfo.flags

                                        & ApplicationInfo.FLAG_DEBUGGABLE) != 0;

                    final boolean downgradePermitted =

                            (downgradeRequested) && ((Build.IS_DEBUGGABLE) || (packageDebuggable));

                    if (!downgradePermitted) {

                        try {

                            checkDowngrade(dataOwnerPkg, pkgLite);

                        } catch (PackageManagerException e) {