Persist sessionStorage on disk.

webkit/dom_storage/webkit_dom_storage.gypi

Index: webkit/dom_storage/webkit_dom_storage.gypi
diff --git a/webkit/dom_storage/webkit_dom_storage.gypi b/webkit/dom_storage/webkit_dom_storage.gypi
index 65df55498728168f8c020539005ee1c4a80c4571..853d9b88575624eb97961882668c5a8d7dbbe268 100644
--- a/webkit/dom_storage/webkit_dom_storage.gypi
+++ b/webkit/dom_storage/webkit_dom_storage.gypi
@@ -11,6 +11,7 @@
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
         '<(DEPTH)/sql/sql.gyp:sql',
+        '<(DEPTH)/third_party/leveldatabase/leveldatabase.gyp:leveldatabase',
         '<(DEPTH)/third_party/sqlite/sqlite.gyp:sqlite',
         '<(DEPTH)/webkit/support/webkit_support.gyp:quota',
       ],
@@ -21,6 +22,8 @@
         'dom_storage_context.h',
         'dom_storage_database.cc',
         'dom_storage_database.h',
+        'dom_storage_database_adapter.cc',
+        'dom_storage_database_adapter.h',
         'dom_storage_host.cc',
         'dom_storage_host.h',
         'dom_storage_map.cc',
@@ -32,6 +35,12 @@
         'dom_storage_task_runner.cc',
         'dom_storage_task_runner.h',
         'dom_storage_types.h',
+        'local_storage_database_adapter.cc',
+        'local_storage_database_adapter.h',
+        'session_storage_database.cc',
+        'session_storage_database.h',
+        'session_storage_database_adapter.cc',
+        'session_storage_database_adapter.h',
       ],
       'conditions': [
         ['inside_chromium_build==0', {