Iterate an array in O(n) rather than O(n^2) time during IDBKey conversion.

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;
+using WebKit::WebVector;
 
 IndexedDBKey::IndexedDBKey()
     : type_(WebIDBKey::NullType),
       date_(0),
       number_(0) {
 }
 
 IndexedDBKey::IndexedDBKey(const WebIDBKey& key) {
   Set(key);
 }
@@ skipping 26 matching lines @@
 
 void IndexedDBKey::SetNumber(double number) {
   type_ = WebIDBKey::NumberType;
   number_ = number;
 }
 
 void IndexedDBKey::Set(const WebIDBKey& key) {
   type_ = key.type();
   array_.clear();
   if (key.type() == WebIDBKey::ArrayType) {
-    for (size_t i = 0; i < key.array().size(); ++i) {
-      array_.push_back(IndexedDBKey(key.array()[i]));
+    WebVector<WebIDBKey> array = key.array();
+    for (size_t i = 0; i < array.size(); ++i) {
+      array_.push_back(IndexedDBKey(array[i]));
     }
   }
   string_ = key.type() == WebIDBKey::StringType ?
                 static_cast<string16>(key.string()) : string16();
   number_ = key.type() == WebIDBKey::NumberType ? key.number() : 0;
   date_ = key.type() == WebIDBKey::DateType ? key.date() : 0;
 }
 
 IndexedDBKey::operator WebIDBKey() const {
   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:
       return WebIDBKey::createInvalid();
     case WebIDBKey::NullType:
       return WebIDBKey::createNull();
   }
   NOTREACHED();
   return WebIDBKey::createInvalid();
 }