Added NavigationManager::GetIndexOfItem().

ios/web/public/test/fakes/test_navigation_manager.mm

 // Copyright 2016 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.
 
 #import "ios/web/public/test/fakes/test_navigation_manager.h"
 
 namespace web {
 
 TestNavigationManager::TestNavigationManager()
     : items_index_(-1),
@@ skipping 57 matching lines @@
 }
 
 int TestNavigationManager::GetItemCount() const {
   return items_.size();
 }
 
 web::NavigationItem* TestNavigationManager::GetItemAtIndex(size_t index) const {
   return items_[index].get();
 }
 
+int TestNavigationManager::GetIndexOfItem(
+    const web::NavigationItem* item) const {
+  for (size_t index = 0; index < items_.size(); ++index) {
+    if (items_[index].get() == item)
+      return index;
+  }
+  return -1;
+}
+
 void TestNavigationManager::SetLastCommittedItemIndex(const int index) {
   DCHECK(index == -1 || index >= 0 && index < GetItemCount());
   items_index_ = index;
 }
 
 int TestNavigationManager::GetLastCommittedItemIndex() const {
   return items_index_;
 }
 
 int TestNavigationManager::GetPendingItemIndex() const {
@@ skipping 67 matching lines @@
 // navigation manager.
 void TestNavigationManager::AddItem(const GURL& url,
                                     ui::PageTransition transition) {
   items_.push_back(web::NavigationItem::Create());
   items_.back()->SetTransitionType(transition);
   items_.back()->SetURL(url);
   SetLastCommittedItemIndex(GetItemCount() - 1);
 }
 
 }  // namespace web