Ensure the xpc transaction is ended

chrome/browser/ui/cocoa/notifications/xpc_transaction_handler.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 <AppKit/AppKit.h>
+#import <Foundation/Foundation.h>
+
+#import "chrome/browser/ui/cocoa/notifications/xpc_transaction_handler.h"
+
+@class NSUserNotificationCenter;
+
+@implementation XPCTransactionHandler {
+  Boolean transactionOpen;

[Robert Sesek, 2016/10/24 23:11:05]

Use BOOL or bool.

[Robert Sesek, 2016/10/24 23:11:05]

naming: needs trailing underscore

[Miguel Garcia, 2016/10/26 15:56:38]

Done.

[Miguel Garcia, 2016/10/26 15:56:38]

Done.

+}
+- (instancetype)init {
+  if ((self = [super init])) {
+    transactionOpen = NO;
+  }
+  return self;
+}
+
+- (void)openTransactionIfNeeded {
+  @synchronized(self) {

[Robert Sesek, 2016/10/24 23:11:05]

Why @synchronized here? I assume we're avoiding base::Lock because of base?

[Miguel Garcia, 2016/10/26 15:56:38]

We need a synchronized block because alerts are added/removed in different
threads.
With that in mind yes, I think we want to stay away from base as much as
possible so doing it natively seemed better.

+    if (transactionOpen) {
+      return;
+    }
+    xpc_transaction_begin();
+    transactionOpen = YES;
+  }
+}
+
+- (void)closeTransactionIfNeeded {
+  @synchronized(self) {
+    NSUserNotificationCenter* notificationCenter =
+        [NSUserNotificationCenter defaultUserNotificationCenter];
+    NSInteger showing = [[notificationCenter deliveredNotifications] count];
+    if (showing == 0) {
+      xpc_transaction_end();
+      transactionOpen = NO;
+    }
+  }
+}
+@end