Expose ro.secure test endpoint for cts.

Bug: 247053706
Test: android.os.cts.BuildTest

Change-Id: If0d0b13a53717d221a7eab8ffbd4b08f71db00c5

core/api/test-current.txt

@@ -1711,6 +1711,7 @@ package android.os {
   public class Build {
     method public static boolean is64BitAbi(String);
     method public static boolean isDebuggable();
+    method public static boolean isSecure();
     field public static final boolean IS_EMULATOR;
   }
 

core/java/android/os/Build.java

@@ -1446,6 +1446,28 @@ public class Build {
         return IS_DEBUGGABLE;
     }
 
+
+    /**
+     * Returns true if the device is running a secure build, such as "user" or "userdebug".
+     *
+     * Secure builds drop adbd privileges by default, though debuggable builds still allow users
+     * to gain root access via local shell. See should_drop_privileges() in adb for details.
+     * @hide
+     */
+    private static final boolean IS_SECURE =
+            SystemProperties.getBoolean("ro.secure", true);
+    /**
+     * Returns true if the device is running a secure build, such as "user" or "userdebug".
+     *
+     * Secure builds drop adbd privileges by default, though debuggable builds still allow users
+     * to gain root access via local shell. See should_drop_privileges() in adb for details.
+     * @hide
+     */
+    @TestApi
+    public static boolean isSecure() {
+        return IS_SECURE;
+    }
+
     /** {@hide} */
     public static final boolean IS_ENG = "eng".equals(TYPE);
     /** {@hide} */