[ios] Add a delegate to WebStateList class.

ios/clean/chrome/browser/model/browser_list.mm

 // Copyright 2017 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/clean/chrome/browser/model/browser_list.h"
 
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#import "ios/clean/chrome/browser/model/browser_web_state_list_delegate.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 const char kBrowserListKey = 0;
 }
 
 BrowserList::BrowserList(ios::ChromeBrowserState* browser_state)
-    : browser_state_(browser_state) {
+    : browser_state_(browser_state),
+      delegate_(base::MakeUnique<BrowserWebStateListDelegate>()) {
   DCHECK(browser_state_);
 }
 
 BrowserList::~BrowserList() = default;
 
 // static
 BrowserList* BrowserList::FromBrowserState(
     ios::ChromeBrowserState* browser_state) {
   base::SupportsUserData::Data* data =
       browser_state->GetUserData(&kBrowserListKey);
@@ skipping 14 matching lines @@
 int BrowserList::ContainsIndex(int index) const {
   return 0 <= index && index < GetBrowserCount();
 }
 
 Browser* BrowserList::GetBrowserAtIndex(int index) const {
   DCHECK(ContainsIndex(index));
   return browsers_[index].get();
 }
 
 Browser* BrowserList::CreateNewBrowser() {
-  browsers_.push_back(base::MakeUnique<Browser>(browser_state_));
+  browsers_.push_back(
+      base::MakeUnique<Browser>(browser_state_, delegate_.get()));
   return browsers_.back().get();
 }
 
 void BrowserList::CloseBrowserAtIndex(int index) {
   DCHECK(ContainsIndex(index));
   browsers_.erase(browsers_.begin() + index);
 }