Fix DialerSettingsActivity so it does not crash pre-M.

UserManager.isSystemUser() is not available pre-M, so we need to copy
over the logic.

Bug: 25776171
Change-Id: I8e7c8e7215a8b55009283ecb137cc54443e61ab8

1 files changed, 37 insertions, 0 deletions

diff --git a/src/com/android/dialer/compat/UserManagerCompat.java b/src/com/android/dialer/compat/UserManagerCompat.java
new file mode 100644
index 000000000..a1fdcc68e
--- /dev/null
+++ b/src/com/android/dialer/compat/UserManagerCompat.java
@@ -0,0 +1,37 @@
+package com.android.dialer.compat;
+
+import android.content.Context;
+import android.os.Process;
+import android.os.UserHandle;
+import android.os.UserManager;
+
+import com.android.contacts.common.compat.CompatUtils;
+
+/**
+ * Compatibility class for {@link UserManager}.
+ */
+public class UserManagerCompat {
+    /**
+     * A user id constant to indicate the "system" user of the device. Copied from
+     * {@link UserHandle}.
+     */
+    private static final int USER_SYSTEM = 0;
+    /**
+     * Range of uids allocated for a user.
+     */
+    private static final int PER_USER_RANGE = 100000;
+
+    /**
+     * Used to check if this process is running under the system user. The system user is the
+     * initial user that is implicitly created on first boot and hosts most of the system services.
+     *
+     * @return whether this process is running under the system user.
+     */
+    public static boolean isSystemUser(UserManager userManager) {
+        if (CompatUtils.isMarshmallowCompatible()) {
+            return userManager.isSystemUser();
+        }
+        // Adapted from {@link UserManager} and {@link UserHandle}.
+        return (Process.myUid() / PER_USER_RANGE) == USER_SYSTEM;
+    }
+}