Do not clear a shared user's permissions on an app install.

When regranting permissions for an app during an install if
that app is in a shared user we should not clear the permissions
as the permissions for the shared user are additive and go away
when apps requesting them are uninstalled.

bug:20050689

Change-Id: I82aa70669fc25a45e7020a1545b093db5525f5cf

services/core/java/com/android/server/pm/PackageManagerService.java

@@ -7397,8 +7397,10 @@ public class PackageManagerService extends IPackageManager.Stub {
 
         if (replace) {
             ps.installPermissionsFixed = false;
-            origPermissions = new PermissionsState(permissionsState);
-            permissionsState.reset();
+            if (!ps.isSharedUser()) {
+                origPermissions = new PermissionsState(permissionsState);
+                permissionsState.reset();
+            }
         }
 
         permissionsState.setGlobalGids(mGlobalGids);

services/core/java/com/android/server/pm/PackageSetting.java

@@ -74,4 +74,8 @@ final class PackageSetting extends PackageSettingBase {
     public boolean isSystem() {
         return (pkgFlags & ApplicationInfo.FLAG_SYSTEM) != 0;
     }
+
+    public boolean isSharedUser() {
+        return sharedUser != null;
+    }
 }