ios: Remove use of MessageLoopProxy and deprecated MessageLoop APIs

ios/net/cookies/cookie_store_ios.mm

Index: ios/net/cookies/cookie_store_ios.mm
diff --git a/ios/net/cookies/cookie_store_ios.mm b/ios/net/cookies/cookie_store_ios.mm
index bd071509c7a7de7eb6c3763eefb6a817d302c78d..b54f731f967a08188e729bbd68051d3bddddf563 100644
--- a/ios/net/cookies/cookie_store_ios.mm
+++ b/ios/net/cookies/cookie_store_ios.mm
@@ -15,13 +15,13 @@
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop_proxy.h"
 #include "base/metrics/histogram.h"
 #include "base/observer_list.h"
 #include "base/sequenced_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/task_runner_util.h"
+#include "base/thread_task_runner_handle.h"
 #include "base/threading/thread_restrictions.h"
 #include "ios/net/cookies/cookie_creation_time_manager.h"
 #include "ios/net/cookies/cookie_store_ios_client.h"
@@ -798,7 +798,7 @@ void CookieStoreIOS::OnSystemCookiesChanged() {
 
   flush_closure_.Reset(base::Bind(&CookieStoreIOS::Flush,
                                   base::Unretained(this), base::Closure()));
-  base::MessageLoopProxy::current()->PostDelayedTask(
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
       FROM_HERE, flush_closure_.callback(), flush_delay_);
 }