[iOS] Upstream //ios/chrome/browser/ui/commands changes

ios/chrome/browser/ui/commands/generic_chrome_command.h

 // Copyright 2012 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_COMMANDS_GENERIC_CHROME_COMMAND_H_
 #define IOS_CHROME_BROWSER_UI_COMMANDS_GENERIC_CHROME_COMMAND_H_
 
 #import <Foundation/Foundation.h>
 
 // Generic command that can be passed to |chromeExecuteCommand|.
 @interface GenericChromeCommand : NSObject
 
-@property(nonatomic, assign) NSInteger tag;
+// Mark inherited initializer as unavailable to prevent calling it by mistake.
+- (instancetype)init NS_UNAVAILABLE;
 
-// Designated initializer.
-- (instancetype)initWithTag:(NSInteger)tag;
+// Initializes the GenericChromeCommand with given |tag|.
+- (instancetype)initWithTag:(NSInteger)tag NS_DESIGNATED_INITIALIZER;
 
 // Convenience method to execute this command on the main window.
 - (void)executeOnMainWindow;
 
+// Command tag.
+@property(nonatomic, assign) NSInteger tag;
+
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_COMMANDS_GENERIC_CHROME_COMMAND_H_