Add isSafeModeEnabled() API to WindowManagerService

This adds a means of determining when the device is in safe mode,
as required by keyguard to disabled some features.

Change-Id: I31d357e6738c92e1837f9e0263e5f3f4de66315a
diff --git a/core/java/android/view/IWindowManager.aidl b/core/java/android/view/IWindowManager.aidl
index 5f598b1..fdaf39e 100644
--- a/core/java/android/view/IWindowManager.aidl
+++ b/core/java/android/view/IWindowManager.aidl
@@ -254,4 +254,9 @@
      * Gets the infos for all visible windows.
      */
     void getVisibleWindowsForDisplay(int displayId, out List<WindowInfo> outInfos);
+
+    /**
+     * Device is in safe mode.
+     */
+    boolean isSafeModeEnabled();
 }