Distinguish null IDBKey (no value) and invalid IDBKey (value is not valid key)

content/common/indexed_db/indexed_db_key.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/indexed_db/indexed_db_key.h"
 
 #include "base/logging.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebVector.h"
 
 using WebKit::WebIDBKey;
 
 IndexedDBKey::IndexedDBKey()
-    : type_(WebIDBKey::InvalidType),
+    : type_(WebIDBKey::NullType),
       date_(0),
       number_(0) {
 }
 
 IndexedDBKey::IndexedDBKey(const WebIDBKey& key) {
   Set(key);
 }
 
 IndexedDBKey::~IndexedDBKey() {
 }
 
 void IndexedDBKey::SetInvalid() {
   type_ = WebIDBKey::InvalidType;
 }
 
+void IndexedDBKey::SetNull() {
+  type_ = WebIDBKey::NullType;
+}
+
 void IndexedDBKey::SetArray(const std::vector<IndexedDBKey>& array) {
   type_ = WebIDBKey::ArrayType;
   array_ = array;
 }
 
 void IndexedDBKey::SetString(const string16& string) {
   type_ = WebIDBKey::StringType;
   string_ = string;
 }
 
@@ skipping 25 matching lines @@
   switch (type_) {
     case WebIDBKey::ArrayType:
       return WebIDBKey::createArray(array_);
     case WebIDBKey::StringType:
       return WebIDBKey::createString(string_);
     case WebIDBKey::DateType:
       return WebIDBKey::createDate(date_);
     case WebIDBKey::NumberType:
       return WebIDBKey::createNumber(number_);
     case WebIDBKey::InvalidType:
-    default:
-      // TODO(jsbell): Remove "default" label once WebKit bug 76487 has rolled.
-      // http://crbug.com/110956
       return WebIDBKey::createInvalid();
+    case WebIDBKey::NullType:
+      return WebIDBKey::createNull();
   }
   NOTREACHED();
   return WebIDBKey::createInvalid();
 }