Bookmark page changes

 Bug: 6372933
 Fix a race condition between update & destroy
 Fix update path
 Add some extra debug support

Change-Id: I66a450e175b22d992de97d5bc24200961144412a
diff --git a/src/com/android/browser/PreferenceKeys.java b/src/com/android/browser/PreferenceKeys.java
index ff42aaf..f7dc0e0 100644
--- a/src/com/android/browser/PreferenceKeys.java
+++ b/src/com/android/browser/PreferenceKeys.java
@@ -76,6 +76,7 @@
     static final String PREF_SMALL_SCREEN = "small_screen";
     static final String PREF_WIDE_VIEWPORT = "wide_viewport";
     static final String PREF_RESET_PRELOGIN = "reset_prelogin";
+    static final String PREF_ADD_BOOKMARKS = "add_bookmarks";
 
     // ----------------------
     // Keys for lab_preferences.xml