Another stab at the Chromium side of storage events. The WebKit side can be ...

chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h

Index: chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
===================================================================
--- chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h	(revision 27652)
+++ chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h	(working copy)
@@ -29,14 +29,22 @@
   // Only call from ResourceMessageFilter on the IO thread.
   void Init(base::ProcessHandle process_handle);
 
+  // Only call from ResourceMessageFilter on the IO thread.  Calls self on the
+  // WebKit thread in some cases.
+  void Shutdown();
+
   // Only call from ResourceMessageFilter on the IO thread.
-  void Shutdown();
   bool OnMessageReceived(const IPC::Message& message, bool *msg_is_ok);
 
   // Send a message to the renderer process associated with our
   // message_sender_ via the IO thread.  May be called from any thread.
   void Send(IPC::Message* message);
 
+  // Only call on the WebKit thread.
+  static void DispatchStorageEvent(const string16& key,
+      const NullableString16& old_value, const NullableString16& new_value,
+      const string16& origin, bool is_local_storage);
+
  private:
   friend class base::RefCountedThreadSafe<DOMStorageDispatcherHost>;
   ~DOMStorageDispatcherHost();
@@ -55,12 +63,27 @@
   void OnRemoveItem(int64 storage_area_id, const string16& key);
   void OnClear(int64 storage_area_id);
 
+  // Only call on the IO thread.
+  void OnStorageEvent(const string16& key, const NullableString16& old_value,
+      const NullableString16& new_value, const string16& origin,
+      bool is_local_storage);
+
   // A shortcut for accessing our context.
   DOMStorageContext* Context() {
     DCHECK(!shutdown_);
-    return webkit_context_->GetDOMStorageContext();
+    return webkit_context_->dom_storage_context();
   }
 
+  // Use whenever there's a chance OnStorageEvent will be called.
+  class AutoSetCurrentDispatcherHost {
+   public:
+    AutoSetCurrentDispatcherHost(DOMStorageDispatcherHost* dispatcher_host);
+    ~AutoSetCurrentDispatcherHost();
+  };
+
+  // Only access on the WebKit thread!  Used for storage events.
+  static DOMStorageDispatcherHost* current_;
+
   // Data shared between renderer processes with the same profile.
   scoped_refptr<WebKitContext> webkit_context_;
 
@@ -87,4 +110,17 @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(DOMStorageDispatcherHost);
 };
 
+#if defined(COMPILER_GCC)
+namespace __gnu_cxx {
+
+template<>
+struct hash<DOMStorageDispatcherHost*> {
+  std::size_t operator()(DOMStorageDispatcherHost* const& p) const {
+    return reinterpret_cast<std::size_t>(p);
+  }
+};
+
+}  // namespace __gnu_cxx
+#endif
+
 #endif  // CHROME_BROWSER_IN_PROCESS_WEBKIT_DOM_STORAGE_DISPATCHER_HOST_H_