Index: /home/user/workspace/chromium/src/content/common/dom_storage_messages.h
===================================================================
--- /home/user/workspace/chromium/src/content/common/dom_storage_messages.h  (revision 179095)
+++ /home/user/workspace/chromium/src/content/common/dom_storage_messages.h  (working copy)
@@ -14,6 +14,9 @@

 // Signals a local storage event.
 IPC_STRUCT_BEGIN(DOMStorageMsg_Event_Params)
+  // The storage action performed: ItemSet, ItemRemoved, ItemsCleared
+  IPC_STRUCT_MEMBER(int, storageAction)
+
   // The key that generated the storage event.  Null if clear() was called.
   IPC_STRUCT_MEMBER(NullableString16, key)

Index: /home/user/workspace/chromium/src/content/renderer/dom_storage/dom_storage_dispatcher.cc
===================================================================
--- /home/user/workspace/chromium/src/content/renderer/dom_storage/dom_storage_dispatcher.cc (revision 179095)
+++ /home/user/workspace/chromium/src/content/renderer/dom_storage/dom_storage_dispatcher.cc (working copy)
@@ -311,6 +311,7 @@

   if (params.namespace_id == dom_storage::kLocalStorageNamespaceId) {
     WebKit::WebStorageEventDispatcher::dispatchLocalStorageEvent(
+        params.storageAction,
         params.key,
         params.old_value,
         params.new_value,
@@ -322,6 +323,7 @@
     WebStorageNamespaceImpl
         session_namespace_for_event_dispatch(params.namespace_id);
     WebKit::WebStorageEventDispatcher::dispatchSessionStorageEvent(
+        params.storageAction,
         params.key,
         params.old_value,
         params.new_value,
Index: /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.cc
===================================================================
--- /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.cc  (revision 179095)
+++ /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.cc  (working copy)
@@ -164,6 +164,7 @@
     const NullableString16& old_value,
     const GURL& page_url) {
   SendDomStorageEvent(area, page_url,
+                      0,
                       NullableString16(key, false),
                       NullableString16(new_value, false),
                       old_value);
@@ -175,6 +176,7 @@
     const string16& old_value,
     const GURL& page_url) {
   SendDomStorageEvent(area, page_url,
+                      1,
                       NullableString16(key, false),
                       NullableString16(true),
                       NullableString16(old_value, false));
@@ -184,6 +186,7 @@
     const dom_storage::DomStorageArea* area,
     const GURL& page_url) {
   SendDomStorageEvent(area, page_url,
+                      2,
                       NullableString16(true),
                       NullableString16(true),
                       NullableString16(true));
@@ -192,6 +195,7 @@
 void DOMStorageMessageFilter::SendDomStorageEvent(
     const dom_storage::DomStorageArea* area,
     const GURL& page_url,
+    int storageAction,
     const NullableString16& key,
     const NullableString16& new_value,
     const NullableString16& old_value) {
@@ -204,6 +208,7 @@
     params.origin = area->origin();
     params.page_url = page_url;
     params.connection_id = connection_dispatching_message_for_;
+    params.storageAction = storageAction;
     params.key = key;
     params.new_value = new_value;
     params.old_value = old_value;
Index: /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.h
===================================================================
--- /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.h   (revision 179095)
+++ /home/user/workspace/chromium/src/content/browser/dom_storage/dom_storage_message_filter.h   (working copy)
@@ -78,6 +78,7 @@
   void SendDomStorageEvent(
       const dom_storage::DomStorageArea* area,
       const GURL& page_url,
+      int storageAction,
       const NullableString16& key,
       const NullableString16& new_value,
       const NullableString16& old_value);