Add a nullable string16 class to base. It combines a string16 + a null param

in order to cover all the possible states of a WebKit string.  For strings
where the null state is not meaninfully different from the empty state, this
class should NOT be used.  There are, however, some cases where we do need to
track null.  LocalStorage is an example.  This class should be a fairly light
weight way to do so.  This change also adds implicit conversion to and from
WebStrings.

This also switches LocalStorage's IPCs over to using this new class.

BUG=17343
TEST=none

Review URL: http://codereview.chromium.org/174484

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@24574 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 6 insertions, 8 deletions

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 d6aff32..abded7c 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.cc
@@ -4,8 +4,8 @@
 
 #include "chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h"
 
+#include "base/nullable_string16.h"
 #include "base/stl_util-inl.h"
-#include "base/string16.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/in_process_webkit/webkit_context.h"
 #include "chrome/browser/in_process_webkit/webkit_thread.h"
@@ -263,9 +263,8 @@ void DOMStorageDispatcherHost::OnKey(int64 storage_area_id, unsigned index,
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   WebStorageArea* storage_area = GetStorageArea(storage_area_id);
   CHECK(storage_area);  // TODO(jorlow): Do better than this.
-  WebString key = storage_area->key(index);
-  ViewHostMsg_DOMStorageKey::WriteReplyParams(reply_msg, (string16)key,
-                                              key.isNull());
+  const NullableString16& key = storage_area->key(index);
+  ViewHostMsg_DOMStorageKey::WriteReplyParams(reply_msg, key);
   Send(reply_msg);
 }
 
@@ -284,9 +283,8 @@ void DOMStorageDispatcherHost::OnGetItem(int64 storage_area_id,
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::WEBKIT));
   WebStorageArea* storage_area = GetStorageArea(storage_area_id);
   CHECK(storage_area);  // TODO(jorlow): Do better than this.
-  WebString value = storage_area->getItem(key);
-  ViewHostMsg_DOMStorageGetItem::WriteReplyParams(reply_msg, (string16)value,
-                                                  value.isNull());
+  const NullableString16& value = storage_area->getItem(key);
+  ViewHostMsg_DOMStorageGetItem::WriteReplyParams(reply_msg, value);
   Send(reply_msg);
 }
 
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 38fee15..c9a6039 100644
--- a/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
+++ b/chrome/browser/in_process_webkit/dom_storage_dispatcher_host.h
@@ -6,8 +6,8 @@
 #define CHROME_BROWSER_IN_PROCESS_WEBKIT_DOM_STORAGE_DISPATCHER_HOST_H_
 
 #include "base/hash_tables.h"
-#include "base/scoped_ptr.h"
 #include "base/ref_counted.h"
+#include "base/scoped_ptr.h"
 #include "ipc/ipc_message.h"
 
 class WebKitContext;