Browser incognito mode session expiration.

Change-Id: I3736ce91bd5ecbcead7a80228680c9fcbf7c374b
diff --git a/src/com/android/browser/Tab.java b/src/com/android/browser/Tab.java
index a9ab058..7c52bb6 100644
--- a/src/com/android/browser/Tab.java
+++ b/src/com/android/browser/Tab.java
@@ -156,6 +156,7 @@
     static final String PARENTTAB = "parentTab";
     static final String APPID = "appid";
     static final String ORIGINALURL = "originalUrl";
+    static final String INCOGNITO = "privateBrowsingEnabled";
 
     // -------------------------------------------------------------------------