[ios] Add a delegate to WebStateList class.

ios/shared/chrome/browser/tabs/web_state_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/shared/chrome/browser/tabs/web_state_list.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#import "ios/shared/chrome/browser/tabs/web_state_list_delegate.h"
 #import "ios/shared/chrome/browser/tabs/web_state_list_observer.h"
 #import "ios/shared/chrome/browser/tabs/web_state_list_order_controller.h"
 #import "ios/web/public/navigation_manager.h"
 #import "ios/web/public/web_state/web_state.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 // Wrapper around a WebState stored in a WebStateList.
@@ skipping 58 matching lines @@
   DCHECK(opener);
   if (opener_ != opener)
     return false;
 
   if (!use_group)
     return true;
 
   return opener_last_committed_index_ == opener_navigation_index;
 }
 
-WebStateList::WebStateList(WebStateOwnership ownership)
-    : web_state_ownership_(ownership),
-      order_controller_(base::MakeUnique<WebStateListOrderController>(this)) {}
+WebStateList::WebStateList(WebStateListDelegate* delegate,
+                           WebStateOwnership ownership)
+    : delegate_(delegate),
+      web_state_ownership_(ownership),
+      order_controller_(base::MakeUnique<WebStateListOrderController>(this)) {
+  DCHECK(delegate_);
+}
 
 WebStateList::~WebStateList() {
   // Once WebStateList owns the WebState and has a CloseWebStateAt() method,
   // then change this to close all the WebState. See http://crbug.com/546222
   // for progress.
   if (web_state_ownership_ == WebStateOwned) {
     for (auto& web_state_wrapper : web_state_wrappers_) {
       web::WebState* web_state = web_state_wrapper->web_state();
       delete web_state;
     }
@@ skipping 43 matching lines @@
 int WebStateList::GetIndexOfLastWebStateOpenedBy(const web::WebState* opener,
                                                  int start_index,
                                                  bool use_group) const {
   return GetIndexOfNthWebStateOpenedBy(opener, start_index, use_group, INT_MAX);
 }
 
 void WebStateList::InsertWebState(int index,
                                   web::WebState* web_state,
                                   web::WebState* opener) {
   DCHECK(ContainsIndex(index) || index == count());
+  delegate_->WillAddWebState(web_state);
+
   web_state_wrappers_.insert(web_state_wrappers_.begin() + index,
                              base::MakeUnique<WebStateWrapper>(web_state));
 
   if (active_index_ >= index)
     ++active_index_;
 
   if (opener)
     SetOpenerOfWebStateAt(index, opener);
 
   for (auto& observer : observers_)
@@ skipping 34 matching lines @@
   }
 
   for (auto& observer : observers_)
     observer.WebStateMoved(this, web_state, from_index, to_index);
 }
 
 web::WebState* WebStateList::ReplaceWebStateAt(int index,
                                                web::WebState* web_state,
                                                web::WebState* opener) {
   DCHECK(ContainsIndex(index));
+  delegate_->WillAddWebState(web_state);
+
   ClearOpenersReferencing(index);
 
   auto& web_state_wrapper = web_state_wrappers_[index];
   web::WebState* old_web_state = web_state_wrapper->ReplaceWebState(web_state);
 
   if (opener && opener != old_web_state)
     SetOpenerOfWebStateAt(index, opener);
 
   for (auto& observer : observers_)
     observer.WebStateReplacedAt(this, old_web_state, web_state, index);
@@ skipping 83 matching lines @@
     } else if (found_index != kInvalidIndex) {
       return found_index;
     }
   }
 
   return found_index;
 }
 
 // static
 const int WebStateList::kInvalidIndex;