Creates coordinators for displaying alerts

ios/chrome/browser/ui/alert_coordinator/alert_controller_coordinator+subclassing.h

Index: ios/chrome/browser/ui/alert_coordinator/alert_controller_coordinator+subclassing.h
diff --git a/ios/chrome/browser/ui/alert_coordinator/alert_controller_coordinator+subclassing.h b/ios/chrome/browser/ui/alert_coordinator/alert_controller_coordinator+subclassing.h
new file mode 100644
index 0000000000000000000000000000000000000000..62df786dda6de7458379b8a74baaee6a1d940584
--- /dev/null
+++ b/ios/chrome/browser/ui/alert_coordinator/alert_controller_coordinator+subclassing.h
@@ -0,0 +1,22 @@
+// 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.
+
+#ifndef IOS_CHROME_BROWSER_UI_ALERT_COORDINATOR_ALERT_CONTROLLER_COORDINATOR_SUBCLASSING_H_
+#define IOS_CHROME_BROWSER_UI_ALERT_COORDINATOR_ALERT_CONTROLLER_COORDINATOR_SUBCLASSING_H_
+
+// Methods used or overrided by the subclasses.
+@interface AlertControllerCoordinator (subclassing)

[lpromero, 2016/07/06 09:03:59]

This looks more like delegate calls. Prefer delegation over subclassing.

[gambard, 2016/07/07 08:57:43]

Done.

+
+// Whether the alert should be displayed or not.
+- (BOOL)shouldStart;
+// Creates the AlertController.

[lpromero, 2016/07/06 09:03:59]

s/AlertController/UIAlertController.

[gambard, 2016/07/07 08:57:43]

Done.

+- (UIAlertController*)createAlertController;

[lpromero, 2016/07/06 09:03:59]

Traditionally, methods starting with `create` returned an object with a retain
count of +1. I am not sure how the static analyzer and ARC interpret it
nowadays. To be on the safe side, prefer renaming it newAlertController,
returning an object with a retain count of +1.

[lpromero, 2016/07/06 09:03:59]

Here too, I'd say createUIAlertController.

[gambard, 2016/07/07 08:57:43]

I have change it to a method delegate name alertCoordinatorUIAlertController and
so it does not give ownership to the caller. Please comment if you think it
could be better.

+// Called when the alert is dismissed to perform cleanup.
+- (void)alertDismissed;
+// If a cancel button should be created at the creation of the alert.
+- (BOOL)shouldCreateCancelButtonAtCreation;

[lpromero, 2016/07/06 09:03:59]

Is the button only created, not added? If added, what about:
shouldDisplayCancelButton?

[gambard, 2016/07/07 08:57:43]

Done.

+
+@end
+
+#endif  // IOS_CHROME_BROWSER_UI_ALERT_COORDINATOR_ALERT_CONTROLLER_COORDINATOR_SUBCLASSING_H_