[ios] Add a delegate to WebStateList class.

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

Index: ios/clean/chrome/browser/model/browser_list.mm
diff --git a/ios/clean/chrome/browser/model/browser_list.mm b/ios/clean/chrome/browser/model/browser_list.mm
index 5a2e57066efdcaddad8cb84e8b61e727e4a0ac07..8c8161ccef04c862ad987012bf5249da1f3ca709 100644
--- a/ios/clean/chrome/browser/model/browser_list.mm
+++ b/ios/clean/chrome/browser/model/browser_list.mm
@@ -9,6 +9,7 @@
 #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."
@@ -19,7 +20,8 @@ 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_);
 }
 
@@ -54,7 +56,8 @@ Browser* BrowserList::GetBrowserAtIndex(int index) const {
 }
 
 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();
 }