Add ContextMenuCoordinator.

ios/chrome/browser/ui/context_menu/context_menu_wrangler.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 "ios/chrome/browser/ui/context_menu/context_menu_wrangler.h"
+
+#include "base/ios/weak_nsobject.h"
+#include "base/strings/sys_string_conversions.h"
+#import "ios/web/public/web_state/context_menu_params.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/strings/grit/ui_strings.h"
+
+@interface ContextMenuWrangler () {
+  // Underlying system alert.
+  base::WeakNSObject<UIAlertController> _alertController;
+  // Parameters that define what is shown in the context menu.
+  web::ContextMenuParams _params;
+}
+// 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
+
+// Displays a context menu.

[Eugene But (OOO till 7-30), 2016/05/13 01:23:55]

Drop this comment. Interface already has documentation.

[michaeldo, 2016/05/17 18:03:03]

Done.

+@implementation ContextMenuWrangler
+@synthesize visible = _visible;
+
+- (instancetype)initWithContextMenuParams:
+    (const web::ContextMenuParams&)params {
+  self = [super init];
+  if (self) {
+    _params = params;
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [_alertController dismissViewControllerAnimated:NO completion:nil];
+  [super dealloc];
+}
+
+- (UIAlertController*)alertController {

[Eugene But (OOO till 7-30), 2016/05/13 01:23:55]

Move to the bottom. Before |alertDismissed|.

[michaeldo, 2016/05/17 18:03:03]

Done.

+  if (!_alertController) {
+    UIAlertController* alert = [UIAlertController
+        alertControllerWithTitle:_params.menu_title
+                         message:nil
+                  preferredStyle:UIAlertControllerStyleActionSheet];
+    alert.popoverPresentationController.sourceView = _params.view;

[marq (ping after 24h), 2016/05/13 14:51:29]

DCHECK at some stage that _params.view is a subview of the presenting view
controller's view?

[michaeldo, 2016/05/17 18:03:03]

I agree, good idea. Done.

+    alert.popoverPresentationController.sourceRect =
+        CGRectMake(_params.location.x, _params.location.y, 1.0, 1.0);
+
+    base::WeakNSObject<ContextMenuWrangler> weakSelf(self);
+    UIAlertAction* cancel_action =

[Eugene But (OOO till 7-30), 2016/05/13 01:23:55]

s/cancel_action/cancelAction

[michaeldo, 2016/05/17 18:03:03]

Done.

+        [UIAlertAction actionWithTitle:l10n_util::GetNSString(IDS_APP_CANCEL)
+                                 style:UIAlertActionStyleCancel
+                               handler:^(UIAlertAction*) {
+                                 [weakSelf alertDismissed];
+                               }];
+    [alert addAction:cancel_action];
+
+    _alertController.reset([alert retain]);
+  }
+  return _alertController;
+}
+
+- (void)addItemWithTitle:(NSString*)title action:(ProceduralBlock)actionBlock {

[marq (ping after 24h), 2016/05/13 14:51:29]

It feels like everything that's added here should really be in the
contextMenuParams.

(modulo whatever decision we make about actions).

[michaeldo, 2016/05/17 18:03:03]

This would go against what chromium is doing, but I do understand what you mean.
I think the use of this entry point will diminish if we can successfully merge
the shared logic. This seems OK to me for now, and we can evaluate the remaining
use cases at that point.

[Eugene But (OOO till 7-30), 2016/05/17 19:37:00]

Web can not be responsible for deciding about the content of the content menu
(f.e. web does not have a concept of Tabs).
Because of that web::ContentMenuParams mirrors content::ContentMenuParams.

+  base::WeakNSObject<ContextMenuWrangler> weakSelf(self);
+  void (^actionHandler)(UIAlertAction*) = ^(UIAlertAction*) {
+    [weakSelf alertDismissed];

[marq (ping after 24h), 2016/05/13 14:51:29]

Annoying that there's no callback or delegate to let us know when the sheet is
done.

[michaeldo, 2016/05/17 18:03:03]

This is in the plans, once migrated to this new class, there is still work to be
done to merge all the similar logic. There is no need right now for the
delegate, so the block is the only current callback.

+    actionBlock();
+  };
+  [self.alertController
+      addAction:[UIAlertAction actionWithTitle:title
+                                         style:UIAlertActionStyleDefault
+                                       handler:actionHandler]];
+}
+
+- (void)present {
+  // Check that the view is still visible on screen, otherwise just return and
+  // don't show the context menu.
+  if (![_params.view window] &&
+      ![_params.view isKindOfClass:[UIWindow class]]) {
+    _alertController.reset();
+    return;
+  }
+
+  // Present sheet/popover using controller that is added to view hierarchy.
+  UIViewController* topController = [_params.view window].rootViewController;
+  while (topController.presentedViewController)
+    topController = topController.presentedViewController;

[marq (ping after 24h), 2016/05/13 14:51:29]

We do this a lot and I regard it as a fairly pernicious antipattern. Much better
to have this object be handed the VC that will present it.

[michaeldo, 2016/05/17 18:03:03]

I agree, will update to pass in the VC.

+  [topController presentViewController:_alertController
+                              animated:YES
+                            completion:nil];
+  self.visible = YES;
+}
+
+- (void)dismissAnimated:(BOOL)animated
+      completionHandler:(ProceduralBlock)completionHandler {
+  [_alertController dismissViewControllerAnimated:animated
+                                       completion:completionHandler];
+  [self setVisible:NO];
+  _alertController.reset();
+}
+
+- (void)alertDismissed {
+  [self setVisible:NO];
+  _alertController.reset();
+}
+
+@end