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

ios/chrome/browser/ui/commands/show_signin_command.mm

+// Copyright 2014 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 "ios/chrome/browser/ui/commands/show_signin_command.h"
+
+#include "base/logging.h"
+#include "base/mac/scoped_block.h"
+#include "ios/chrome/browser/ui/commands/ios_command_ids.h"
+
+@implementation ShowSigninCommand {
+  base::mac::ScopedBlock<ShowSigninCommandCompletionCallback> _callback;
+}
+
+@synthesize operation = _operation;
+@synthesize signInSource = _signInSource;
+
+- (instancetype)initWithTag:(NSInteger)tag {
+  NOTREACHED();
+  return nil;
+}
+
+- (instancetype)initWithOperation:(AuthenticationOperation)operation
+                     signInSource:(SignInSource)signInSource
+                         callback:
+                             (ShowSigninCommandCompletionCallback)callback {
+  if ((self = [super initWithTag:IDC_SHOW_SIGNIN_IOS])) {
+    _operation = operation;
+    _signInSource = signInSource;
+    _callback.reset(callback, base::scoped_policy::RETAIN);
+  }
+  return self;
+}
+
+- (instancetype)initWithOperation:(AuthenticationOperation)operation
+                     signInSource:(SignInSource)signInSource {
+  return
+      [self initWithOperation:operation signInSource:signInSource callback:nil];
+}
+
+- (ShowSigninCommandCompletionCallback)callback {
+  return _callback.get();
+}
+
+@end