Replace base::NullableString16(bool) usage with default constructor.

webkit/browser/dom_storage/dom_storage_area.cc

Index: webkit/browser/dom_storage/dom_storage_area.cc
diff --git a/webkit/browser/dom_storage/dom_storage_area.cc b/webkit/browser/dom_storage/dom_storage_area.cc
index 216c7a41c7fc9d0f2fb58e5c696023f22de84699..51a97db1a5a55a3db967103b4c65c63ea7979ce2 100644
--- a/webkit/browser/dom_storage/dom_storage_area.cc
+++ b/webkit/browser/dom_storage/dom_storage_area.cc
@@ -115,14 +115,14 @@ unsigned DomStorageArea::Length() {
 
 base::NullableString16 DomStorageArea::Key(unsigned index) {
   if (is_shutdown_)
-    return base::NullableString16(true);
+    return base::NullableString16();
   InitialImportIfNeeded();
   return map_->Key(index);
 }
 
 base::NullableString16 DomStorageArea::GetItem(const base::string16& key) {
   if (is_shutdown_)
-    return base::NullableString16(true);
+    return base::NullableString16();
   InitialImportIfNeeded();
   return map_->GetItem(key);
 }
@@ -153,7 +153,7 @@ bool DomStorageArea::RemoveItem(const base::string16& key,
   bool success = map_->RemoveItem(key, old_value);
   if (success && backing_) {
     CommitBatch* commit_batch = CreateCommitBatchIfNeeded();
-    commit_batch->changed_values[key] = base::NullableString16(true);
+    commit_batch->changed_values[key] = base::NullableString16();
   }
   return success;
 }