Reverting 27756.

Review URL: http://codereview.chromium.org/249058

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27759 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 34 insertions, 189 deletions

diff --git a/chrome/browser/in_process_webkit/browser_webkitclient_impl.cc b/chrome/browser/in_process_webkit/browser_webkitclient_impl.cc
index 53ced24..33fc0de 100644
--- a/chrome/browser/in_process_webkit/browser_webkitclient_impl.cc
+++ b/chrome/browser/in_process_webkit/browser_webkitclient_impl.cc
@@ -5,7 +5,6 @@
 #include "chrome/browser/in_process_webkit/browser_webkitclient_impl.h"
 
 #include "base/logging.h"
-#include "chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h"
 #include "webkit/api/public/WebData.h"
 #include "webkit/api/public/WebString.h"
 #include "webkit/api/public/WebURL.h"
@@ -106,15 +105,3 @@ BrowserWebKitClientImpl::createSessionStorageNamespace() {
   NOTREACHED();
   return 0;
 }
-
-void BrowserWebKitClientImpl::dispatchStorageEvent(
-    const WebKit::WebString& key, const WebKit::WebString& old_value,
-    const WebKit::WebString& new_value, const WebKit::WebString& origin,
-    bool is_local_storage) {
-  // TODO(jorlow): Implement
-  if (!is_local_storage)
-    return;
-
-  DOMStorageDispatcherHost::DispatchStorageEvent(key, old_value, new_value,
-                                                 origin, is_local_storage);
-}
diff --git a/chrome/browser/in_process_webkit/browser_webkitclient_impl.h b/chrome/browser/in_process_webkit/browser_webkitclient_impl.h
index 07824db..546100d 100644
--- a/chrome/browser/in_process_webkit/browser_webkitclient_impl.h
+++ b/chrome/browser/in_process_webkit/browser_webkitclient_impl.h
@@ -32,9 +32,6 @@ class BrowserWebKitClientImpl : public webkit_glue::WebKitClientImpl {
   virtual WebKit::WebStorageNamespace* createLocalStorageNamespace(
       const WebKit::WebString& path);
   virtual WebKit::WebStorageNamespace* createSessionStorageNamespace();
-  virtual void dispatchStorageEvent(const WebKit::WebString& key,
-      const WebKit::WebString& oldValue, const WebKit::WebString& newValue,
-      const WebKit::WebString& origin, bool isLocalStorage);
 };
 
 #endif  // CHROME_BROWSER_IN_PROCESS_WEBKIT_WEBKIT_CLIENT_IMPL_H_
diff --git a/chrome/browser/in_process_webkit/dom_storage_context.cc b/chrome/browser/in_process_webkit/dom_storage_context.cc
index 9f763e2..b22d976 100644
--- a/chrome/browser/in_process_webkit/dom_storage_context.cc
+++ b/chrome/browser/in_process_webkit/dom_storage_context.cc
@@ -14,18 +14,11 @@ DOMStorageContext::DOMStorageContext(WebKitContext* webkit_context)
     : last_storage_area_id_(kFirstStorageAreaId),
       last_storage_namespace_id_(kFirstStorageNamespaceId),
       webkit_context_(webkit_context) {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
 }
 
 DOMStorageContext::~DOMStorageContext() {
-  // This should not go away until all DOM Storage Dispatcher hosts have gone
-  // away.  And they remove themselves from this list.
-  DCHECK(dispatcher_host_set_.empty());
-
-  // If we don't have any work to do on the WebKit thread, bail.
-  if (storage_namespace_map_.empty())
-    return;
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
-
   // The storage namespace destructor unregisters the storage namespace, so
   // our iterator becomes invalid.  Thus we just keep deleting the first item
   // until there are none left.
@@ -34,7 +27,6 @@ DOMStorageContext::~DOMStorageContext() {
 }
 
 StorageNamespace* DOMStorageContext::LocalStorage() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   StorageNamespace* storage_namespace = GetStorageNamespace(
       kLocalStorageNamespaceId);
   if (storage_namespace)
@@ -48,26 +40,22 @@ StorageNamespace* DOMStorageContext::LocalStorage() {
 }
 
 StorageNamespace* DOMStorageContext::NewSessionStorage() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   return StorageNamespace::CreateSessionStorageNamespace(this);
 }
 
 void DOMStorageContext::RegisterStorageArea(StorageArea* storage_area) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   int64 id = storage_area->id();
   DCHECK(!GetStorageArea(id));
   storage_area_map_[id] = storage_area;
 }
 
 void DOMStorageContext::UnregisterStorageArea(StorageArea* storage_area) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   int64 id = storage_area->id();
   DCHECK(GetStorageArea(id));
   storage_area_map_.erase(id);
 }
 
 StorageArea* DOMStorageContext::GetStorageArea(int64 id) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   StorageAreaMap::iterator iter = storage_area_map_.find(id);
   if (iter == storage_area_map_.end())
     return NULL;
@@ -76,7 +64,6 @@ StorageArea* DOMStorageContext::GetStorageArea(int64 id) {
 
 void DOMStorageContext::RegisterStorageNamespace(
     StorageNamespace* storage_namespace) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   int64 id = storage_namespace->id();
   DCHECK(!GetStorageNamespace(id));
   storage_namespace_map_[id] = storage_namespace;
@@ -84,38 +71,14 @@ void DOMStorageContext::RegisterStorageNamespace(
 
 void DOMStorageContext::UnregisterStorageNamespace(
     StorageNamespace* storage_namespace) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   int64 id = storage_namespace->id();
   DCHECK(GetStorageNamespace(id));
   storage_namespace_map_.erase(id);
 }
 
 StorageNamespace* DOMStorageContext::GetStorageNamespace(int64 id) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   StorageNamespaceMap::iterator iter = storage_namespace_map_.find(id);
   if (iter == storage_namespace_map_.end())
     return NULL;
   return iter->second;
 }
-
-void DOMStorageContext::RegisterDispatcherHost(
-    DOMStorageDispatcherHost* dispatcher_host) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  DCHECK(dispatcher_host_set_.find(dispatcher_host) ==
-         dispatcher_host_set_.end());
-  dispatcher_host_set_.insert(dispatcher_host);
-}
-
-void DOMStorageContext::UnregisterDispatcherHost(
-    DOMStorageDispatcherHost* dispatcher_host) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  DCHECK(dispatcher_host_set_.find(dispatcher_host) !=
-         dispatcher_host_set_.end());
-  dispatcher_host_set_.erase(dispatcher_host);
-}
-
-const DOMStorageContext::DispatcherHostSet*
-DOMStorageContext::GetDispatcherHostSet() const {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  return &dispatcher_host_set_;
-}
diff --git a/chrome/browser/in_process_webkit/dom_storage_context.h b/chrome/browser/in_process_webkit/dom_storage_context.h
index 5e85876..ba26ac2 100644
--- a/chrome/browser/in_process_webkit/dom_storage_context.h
+++ b/chrome/browser/in_process_webkit/dom_storage_context.h
@@ -7,7 +7,6 @@
 
 #include "base/file_path.h"
 #include "base/hash_tables.h"
-#include "chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h"
 
 class StorageArea;
 class StorageNamespace;
@@ -16,8 +15,7 @@ class WebKitContext;
 // This is owned by WebKitContext and is all the dom storage information that's
 // shared by all the ResourceMessageFilter/DOMStorageDispatcherHosts that share
 // the same profile.  The specifics of responsibilities are fairly well
-// documented here and in StorageNamespace and StorageArea.  Everything is only
-// to be accessed on the WebKit thread unless noted otherwise.
+// documented here and in StorageNamespace and StorageArea.
 class DOMStorageContext {
  public:
   explicit DOMStorageContext(WebKitContext* webkit_context);
@@ -46,13 +44,6 @@ class DOMStorageContext {
   void UnregisterStorageNamespace(StorageNamespace* storage_namespace);
   StorageNamespace* GetStorageNamespace(int64 id);
 
-  // Sometimes an event from one DOM storage dispatcher host requires
-  // communication to all of them.
-  typedef base::hash_set<DOMStorageDispatcherHost*> DispatcherHostSet;
-  void RegisterDispatcherHost(DOMStorageDispatcherHost* dispatcher_host);
-  void UnregisterDispatcherHost(DOMStorageDispatcherHost* dispatcher_host);
-  const DispatcherHostSet* GetDispatcherHostSet() const;
-
   // The special ID used for local storage.
   static const int64 kLocalStorageNamespaceId = 0;
 
@@ -66,10 +57,6 @@ class DOMStorageContext {
   // We're owned by this WebKit context.  Used while instantiating LocalStorage.
   WebKitContext* webkit_context_;
 
-  // All the DOMStorageDispatcherHosts that are attached to us. ONLY USE ON THE
-  // IO THREAD!
-  DispatcherHostSet dispatcher_host_set_;
-
   // Maps ids to StorageAreas.  We do NOT own these objects.  StorageNamespace
   // (which does own them) will notify us when we should remove the entries.
   typedef base::hash_map<int64, StorageArea*> StorageAreaMap;
diff --git a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
index 1856a37..ac39acb 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
@@ -13,23 +13,6 @@
 #include "chrome/browser/renderer_host/browser_render_process_host.h"
 #include "chrome/common/render_messages.h"
 
-DOMStorageDispatcherHost* DOMStorageDispatcherHost::current_ = NULL;
-
-DOMStorageDispatcherHost::
-AutoSetCurrentDispatcherHost::AutoSetCurrentDispatcherHost(
-    DOMStorageDispatcherHost* dispatcher_host) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
-  DCHECK(!current_);
-  current_ = dispatcher_host;
-}
-
-DOMStorageDispatcherHost::
-AutoSetCurrentDispatcherHost::~AutoSetCurrentDispatcherHost() {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
-  DCHECK(current_);
-  current_ = NULL;
-}
-
 DOMStorageDispatcherHost::DOMStorageDispatcherHost(
     IPC::Message::Sender* message_sender, WebKitContext* webkit_context,
     WebKitThread* webkit_thread)
@@ -49,9 +32,6 @@ DOMStorageDispatcherHost::~DOMStorageDispatcherHost() {
 }
 
 void DOMStorageDispatcherHost::Init(base::ProcessHandle process_handle) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  Context()->RegisterDispatcherHost(this);
-
   DCHECK(!process_handle_);
   process_handle_ = process_handle;
   DCHECK(process_handle_);
@@ -59,7 +39,6 @@ void DOMStorageDispatcherHost::Init(base::ProcessHandle process_handle) {
 
 void DOMStorageDispatcherHost::Shutdown() {
   if (ChromeThread::CurrentlyOn(ChromeThread::IO)) {
-    Context()->UnregisterDispatcherHost(this);
     message_sender_ = NULL;
     if (!ever_used_) {
       // No need to (possibly) spin up the WebKit thread for a no-op.
@@ -79,24 +58,12 @@ void DOMStorageDispatcherHost::Shutdown() {
   DCHECK(!shutdown_);
   shutdown_ = true;
 
-  // TODO(jorlow): Do stuff that needs to be run on the WebKit thread.  Locks
-  //               and others will likely need this, so let's not delete this
-  //               code even though it doesn't do anyting yet.
+  // TODO(jorlow): If we have any locks or are tracking resources that need to
+  //               be released on the WebKit thread, do it here.
 }
 
-/* static */
-void DOMStorageDispatcherHost::DispatchStorageEvent(const string16& key,
-    const NullableString16& old_value, const NullableString16& new_value,
-    const string16& origin, bool is_local_storage) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
-  DCHECK(current_);
-  current_->webkit_thread_->PostIOThreadTask(FROM_HERE, NewRunnableMethod(
-        current_, &DOMStorageDispatcherHost::OnStorageEvent, key, old_value,
-        new_value, origin, is_local_storage));
-}
-
-bool DOMStorageDispatcherHost::OnMessageReceived(const IPC::Message& message,
-                                                 bool *msg_is_ok) {
+bool DOMStorageDispatcherHost::OnMessageReceived(
+    const IPC::Message& message, bool *msg_is_ok) {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
   DCHECK(!shutdown_);
   DCHECK(process_handle_);
@@ -305,8 +272,6 @@ void DOMStorageDispatcherHost::OnSetItem(int64 storage_area_id,
         ViewHostMsg_DOMStorageSetItem::ID, process_handle_);
     return;
   }
-
-  AutoSetCurrentDispatcherHost auto_set(this);
   storage_area->SetItem(key, value, &quota_exception);
   DCHECK(!quota_exception);  // This is tracked by the renderer.
 }
@@ -328,8 +293,6 @@ void DOMStorageDispatcherHost::OnRemoveItem(int64 storage_area_id,
         ViewHostMsg_DOMStorageRemoveItem::ID, process_handle_);
     return;
   }
-
-  AutoSetCurrentDispatcherHost auto_set(this);
   storage_area->RemoveItem(key);
 }
 
@@ -349,24 +312,5 @@ void DOMStorageDispatcherHost::OnClear(int64 storage_area_id) {
         ViewHostMsg_DOMStorageClear::ID, process_handle_);
     return;
   }
-
-  AutoSetCurrentDispatcherHost auto_set(this);
   storage_area->Clear();
 }
-
-void DOMStorageDispatcherHost::OnStorageEvent(const string16& key,
-    const NullableString16& old_value, const NullableString16& new_value,
-    const string16& origin, bool is_local_storage) {
-  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
-  DCHECK(is_local_storage);  // Only LocalStorage is implemented right now.
-  DOMStorageType dom_storage_type = is_local_storage ? DOM_STORAGE_LOCAL
-                                                     : DOM_STORAGE_SESSION;
-  const DOMStorageContext::DispatcherHostSet* set =
-      Context()->GetDispatcherHostSet();
-  DOMStorageContext::DispatcherHostSet::const_iterator cur = set->begin();
-  while (cur != set->end()) {
-    (*cur)->Send(new ViewMsg_DOMStorageEvent(key, old_value, new_value, origin,
-                                             dom_storage_type));
-    ++cur;
-  }
-}
diff --git a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
index 7b34ad7..a0d3d77 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
@@ -29,22 +29,14 @@ class DOMStorageDispatcherHost :
   // 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();
@@ -63,27 +55,12 @@ class DOMStorageDispatcherHost :
   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_->dom_storage_context();
+    return webkit_context_->GetDOMStorageContext();
   }
 
-  // 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_;
 
@@ -110,17 +87,4 @@ class DOMStorageDispatcherHost :
   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_
diff --git a/chrome/browser/in_process_webkit/storage_namespace.cc b/chrome/browser/in_process_webkit/storage_namespace.cc
index fb49259..fa2c74a 100644
--- a/chrome/browser/in_process_webkit/storage_namespace.cc
+++ b/chrome/browser/in_process_webkit/storage_namespace.cc
@@ -42,11 +42,11 @@ StorageNamespace* StorageNamespace::CreateSessionStorageNamespace(
 
 StorageNamespace::StorageNamespace(DOMStorageContext* dom_storage_context,
                                    WebStorageNamespace* storage_namespace,
-                                   int64 id, DOMStorageType dom_storage_type)
+                                   int64 id, DOMStorageType storage_type)
     : dom_storage_context_(dom_storage_context),
       storage_namespace_(storage_namespace),
       id_(id),
-      dom_storage_type_(dom_storage_type) {
+      storage_type_(storage_type) {
   DCHECK(dom_storage_context_);
   DCHECK(storage_namespace_);
   dom_storage_context_->RegisterStorageNamespace(this);
@@ -82,12 +82,12 @@ StorageArea* StorageNamespace::GetStorageArea(const string16& origin) {
 }
 
 StorageNamespace* StorageNamespace::Copy() {
-  DCHECK(dom_storage_type_ == DOM_STORAGE_SESSION);
+  DCHECK(storage_type_ == DOM_STORAGE_SESSION);
   int64 id = dom_storage_context_->AllocateStorageNamespaceId();
   DCHECK(!dom_storage_context_->GetStorageNamespace(id));
   WebStorageNamespace* new_storage_namespace = storage_namespace_->copy();
   return new StorageNamespace(dom_storage_context_, new_storage_namespace, id,
-                              dom_storage_type_);
+                              storage_type_);
 }
 
 void StorageNamespace::Close() {
diff --git a/chrome/browser/in_process_webkit/storage_namespace.h b/chrome/browser/in_process_webkit/storage_namespace.h
index 9752212..91e0ae6 100644
--- a/chrome/browser/in_process_webkit/storage_namespace.h
+++ b/chrome/browser/in_process_webkit/storage_namespace.h
@@ -31,11 +31,7 @@ class StorageNamespace {
   StorageNamespace* Copy();
   void Close();
 
-  const DOMStorageContext* dom_storage_context() const {
-    return dom_storage_context_;
-  }
   int64 id() const { return id_; }
-  DOMStorageType dom_storage_type() const { return dom_storage_type_; }
 
  private:
   // Called by the static factory methods above.
@@ -57,7 +53,7 @@ class StorageNamespace {
   int64 id_;
 
   // SessionStorage vs. LocalStorage.
-  const DOMStorageType dom_storage_type_;
+  const DOMStorageType storage_type_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StorageNamespace);
 };
diff --git a/chrome/browser/in_process_webkit/webkit_context.cc b/chrome/browser/in_process_webkit/webkit_context.cc
index 0768284..ae647d6 100644
--- a/chrome/browser/in_process_webkit/webkit_context.cc
+++ b/chrome/browser/in_process_webkit/webkit_context.cc
@@ -9,17 +9,24 @@
 
 WebKitContext::WebKitContext(const FilePath& data_path, bool is_incognito)
     : data_path_(data_path),
-      is_incognito_(is_incognito),
-      ALLOW_THIS_IN_INITIALIZER_LIST(
-          dom_storage_context_(new DOMStorageContext(this))) {
+      is_incognito_(is_incognito) {
 }
 
 WebKitContext::~WebKitContext() {
-  // If the WebKit thread was ever spun up, delete the object there.  If we're
-  // on the IO thread, this is safe because the WebKit thread goes away after
-  // the IO.  If we're on the UI thread, we're safe because the UI thread kills
-  // the WebKit thread.
-  MessageLoop* webkit_loop = ChromeThread::GetMessageLoop(ChromeThread::WEBKIT);
-  if (webkit_loop)
-    webkit_loop->DeleteSoon(FROM_HERE, dom_storage_context_.release());
+  // If a dom storage context was ever created, we need to destroy it on the
+  // WebKit thread.  Luckily we're guaranteed that the WebKit thread is still
+  // alive since the ResourceDispatcherHost (which owns the WebKit thread) goes
+  // away after all the ResourceMessageFilters and the profiles (i.e. all the
+  // objects with a reference to us).
+  if (dom_storage_context_.get()) {
+    MessageLoop* loop = ChromeThread::GetMessageLoop(ChromeThread::WEBKIT);
+    loop->DeleteSoon(FROM_HERE, dom_storage_context_.release());
+  }
+}
+
+DOMStorageContext* WebKitContext::GetDOMStorageContext() {
+  DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
+  if (!dom_storage_context_.get())
+    dom_storage_context_.reset(new DOMStorageContext(this));
+  return dom_storage_context_.get();
 }
diff --git a/chrome/browser/in_process_webkit/webkit_context.h b/chrome/browser/in_process_webkit/webkit_context.h
index b359ab0..ee4c61b 100644
--- a/chrome/browser/in_process_webkit/webkit_context.h
+++ b/chrome/browser/in_process_webkit/webkit_context.h
@@ -10,7 +10,6 @@
 #include "base/scoped_ptr.h"
 
 class DOMStorageContext;
-class WebKitThread;
 
 // There's one WebKitContext per profile.  Various DispatcherHost classes
 // have a pointer to the Context to store shared state.
@@ -20,9 +19,9 @@ class WebKitContext : public base::RefCountedThreadSafe<WebKitContext> {
 
   const FilePath& data_path() const { return data_path_; }
   bool is_incognito() const { return is_incognito_; }
-  DOMStorageContext* dom_storage_context() {
-    return dom_storage_context_.get();
-  }
+
+  // Initialized lazily.  Pointer is valid for the lifetime of this instance.
+  DOMStorageContext* GetDOMStorageContext();
 
  private:
   friend class base::RefCountedThreadSafe<WebKitContext>;
@@ -32,6 +31,7 @@ class WebKitContext : public base::RefCountedThreadSafe<WebKitContext> {
   const FilePath data_path_;
   const bool is_incognito_;
 
+  // The state for DOM Storage.
   scoped_ptr<DOMStorageContext> dom_storage_context_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(WebKitContext);