Added SDL_IsChromebook() to determine if we're running on a Chromebook.

android-project/app/src/main/java/org/libsdl/app/SDLActivity.java

@@ -695,6 +695,13 @@ public class SDLActivity extends Activity {
         return (uiModeManager.getCurrentModeType() == Configuration.UI_MODE_TYPE_TELEVISION);
     }
 
+    /**
+     * This method is called by SDL using JNI.
+     */
+    public static boolean isChromebook() {
+        return getContext().getPackageManager().hasSystemFeature("org.chromium.arc.device_management");
+    }    
+
     /**
      * This method is called by SDL using JNI.
      */