Creates coordinators for displaying alerts

ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm

Index: ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm
diff --git a/ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm b/ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm
new file mode 100644
index 0000000000000000000000000000000000000000..9c1aecf8e97fd020ae3bb35cf9d776e0cbc9877c
--- /dev/null
+++ b/ios/chrome/browser/ui/alert_coordinator/alert_coordinator.mm
@@ -0,0 +1,159 @@
+// 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 "ios/chrome/browser/ui/alert_coordinator/alert_coordinator.h"
+
+#import "base/ios/weak_nsobject.h"
+#import "base/mac/scoped_nsobject.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/strings/grit/ui_strings.h"
+
+@interface AlertCoordinator () {
+  // Variables backing properties of the same name.
+  base::scoped_nsobject<UIAlertController> _alertController;
+  base::scoped_nsobject<NSString> _message;
+
+  // Title for the alert.
+  base::scoped_nsobject<NSString> _title;
+  // Rectangle for the popover alert.
+  CGRect _rect;
+  // View for the popovert alert.
+  base::scoped_nsobject<UIView> _view;
+  // Style for this alert.
+  UIAlertControllerStyle _style;
+}
+
+// Redefined to readwrite.
+@property(nonatomic, readwrite, getter=isVisible) BOOL visible;
+// Lazy initializer to create the |_alert|.
+@property(nonatomic, readonly) UIAlertController* alertController;
+
+// Called when the alert is dismissed to perform cleanup.
+- (void)alertDismissed;
+
+@end
+
+@implementation AlertCoordinator
+
+@synthesize visible = _visible;
+@synthesize cancelButtonAdded = _cancelButtonAdded;
+
+- (instancetype)initWithBaseViewController:(UIViewController*)viewController {
+  NOTREACHED();
+  return nil;
+}
+
+- (instancetype)initWithBaseViewController:(UIViewController*)viewController
+                                     title:(NSString*)title {
+  self = [super initWithBaseViewController:viewController];
+  if (self) {
+    _style = UIAlertControllerStyleAlert;
+    _title.reset([title copy]);
+  }
+  return self;
+}
+
+#pragma mark - Public Methods.
+
+- (void)configureForActionSheetWithRect:(CGRect)rect popoverView:(UIView*)view {
+  if (_alertController)
+    return;
+
+  _style = UIAlertControllerStyleActionSheet;
+  _view.reset([view retain]);
+  _rect = rect;
+}
+
+- (void)addItemWithTitle:(NSString*)title
+                  action:(ProceduralBlock)actionBlock
+                   style:(UIAlertActionStyle)style {
+  if (self.visible ||
+      (style == UIAlertActionStyleCancel && self.cancelButtonAdded)) {
+    return;
+  }
+
+  if (style == UIAlertActionStyleCancel)
+    _cancelButtonAdded = YES;
+
+  base::WeakNSObject<AlertCoordinator> weakSelf(self);
+
+  UIAlertAction* alertAction =
+      [UIAlertAction actionWithTitle:title
+                               style:style
+                             handler:^(UIAlertAction*) {
+                               [weakSelf alertDismissed];
+                               if (actionBlock)
+                                 actionBlock();
+                             }];
+
+  [self.alertController addAction:alertAction];
+}
+
+- (void)start {
+  // Check that the view is still visible on screen, otherwise just return and
+  // don't show the context menu.
+  if (![self.baseViewController.view window] &&
+      ![self.baseViewController.view isKindOfClass:[UIWindow class]]) {
+    return;
+  }
+
+  // Display at least one button to let the user dismiss the alert.
+  if ([self actionsCount] == 0) {
+    [self addItemWithTitle:l10n_util::GetNSString(IDS_APP_OK)
+                    action:nil
+                     style:UIAlertActionStyleDefault];
+  }
+
+  [self.baseViewController presentViewController:self.alertController
+                                        animated:YES
+                                      completion:nil];
+  self.visible = YES;
+}
+
+- (void)stop {
+  [_alertController dismissViewControllerAnimated:NO completion:nil];
+  [self alertDismissed];
+}
+
+- (NSUInteger)actionsCount {
+  return [_alertController actions].count;
+}
+
+#pragma mark - Property Implementation.
+
+- (UIAlertController*)alertController {
+  if (!_alertController) {
+    UIAlertController* alert =
+        [UIAlertController alertControllerWithTitle:_title
+                                            message:_message
+                                     preferredStyle:_style];
+
+    if (alert)
+      _alertController.reset([alert retain]);
+
+    if (_style == UIAlertControllerStyleActionSheet) {
+      alert.popoverPresentationController.sourceView = _view;
+      alert.popoverPresentationController.sourceRect = _rect;
+    }
+  }
+  return _alertController;
+}
+
+- (NSString*)message {
+  return _message;
+}
+
+- (void)setMessage:(NSString*)message {
+  _message.reset([message copy]);
+}
+
+#pragma mark - Private Methods.
+
+- (void)alertDismissed {
+  self.visible = NO;
+  _cancelButtonAdded = NO;
+  _alertController.reset();
+}
+
+@end