[iOS Clean] Removed old overlay implementation.

ios/shared/chrome/browser/ui/coordinators/browser_coordinator+internal.h

 // 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_SHARED_CHROME_BROWSER_UI_COORDINATORS_BROWSER_COORDINATOR_INTERNAL_H_
 #define IOS_SHARED_CHROME_BROWSER_UI_COORDINATORS_BROWSER_COORDINATOR_INTERNAL_H_
 
 #import "ios/shared/chrome/browser/ui/coordinators/browser_coordinator.h"
 
 // Internal API for subclasses and categories of BrowserCoordinator.
-//
-// This API can be used to create and manage 'overlay coordinators'.
-// Overlay coordinators are intended to be used for UI elements that
-// sit on top of the regular UI, and which may need to be dismissed
-// by coordinators that don't have direct access to them. Typical uses
-// would be alerts, login prompts, or other UI that might be dismissed
-// if (for example) an external event causes a web page to load.
-// Overlay coordinators can be added by any coordinator in the coordinator
-// hierarchy, but they will be children of (generally) the topmost
-// coordinator, regardless of which coordinator added them.
 @interface BrowserCoordinator (Internal)
 
 // Managed view controller of this object. Subclasses must define a
 // property named |viewController| that has the specific UIViewController
 // subclass they use; the subclass API will be able to access that view
 // controller through this property.
 @property(nonatomic, readonly) UIViewController* viewController;
 
 // The child coordinators of this coordinator. To add or remove from this set,
 // use the -addChildCoordinator: and -removeChildCoordinator: methods.
 @property(nonatomic, readonly) NSSet<BrowserCoordinator*>* children;
 
 // The coordinator that added this coordinator as a child, if any.
 @property(nonatomic, readonly) BrowserCoordinator* parentCoordinator;
 
 // YES if the receiver has been started; NO (the default) otherwise. Stopping
 // the receiver resets this property to NO.
 @property(nonatomic, readonly) BOOL started;
 
-// YES if the receiver is acting as an overlay coordinator; NO (the default)
-// otherwise.
-@property(nonatomic, readonly) BOOL overlaying;
-
-// The coordinator (if any) in the coordinator hierarchy (starting with
-// the receiver) that is overlaying. If the receiver isn't overlaying,
-// it recursively asks its children.
-@property(nonatomic, readonly) BrowserCoordinator* overlayCoordinator;
-
 // Adds |coordinator| as a child, taking ownership of it, setting the receiver's
 // viewController (if any) as the child's baseViewController, and setting
 // the receiver's |browser| as the child's |browser|.
 - (void)addChildCoordinator:(BrowserCoordinator*)childCoordinator;
 
 // Removes |coordinator| as a child, relinquishing ownership of it. If
 // |coordinator| isn't a child of the receiver, this method does nothing.
 - (void)removeChildCoordinator:(BrowserCoordinator*)childCoordinator;
 
 // Called when this coordinator is added to a parent coordinator.
 - (void)wasAddedToParentCoordinator:(BrowserCoordinator*)parentCoordinator;
 
 // Called when this coordinator is going to be removed from its parent
 // coordinator.
 - (void)willBeRemovedFromParentCoordinator;
 
 // Called when a child coordinator did start. This is a blank template method.
 // Subclasses can override this method when they need to know when their
 // children start.
 - (void)childCoordinatorDidStart:(BrowserCoordinator*)childCoordinator;
 
 // Called when a child coordinator will stop. This is a blank template method.
 // Subclasses can override this method when they need to know when their
 // children start.
 - (void)childCoordinatorWillStop:(BrowserCoordinator*)childCoordinator;
 
-// Methods for adding overlay coordinators.
-
-// Returns YES if the receiver will take |overlayCoordinator| as a child.
-// The default is to return YES only if the receiver has no children, if
-// the receiver has a nil -overlayCoordinator, and if |overlayCoordinator|
-// is not already overlaying.
-- (BOOL)canAddOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator;
-
-// Adds |overlayCoordinator| as a child to the receiver, or if it cannot be
-// added, recursively add it to the receiver's child. If a receiver has
-// multiple children and returns YES from -canAddOverlayCoordinator:, it
-// must override this method to determines how the overlay is added.
-// If neither the receiver or any child can add |overlayCoordinator|, then
-// nothing happens.
-- (void)addOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator;
-
-// Removes the current overlay coordinator (if any) as a child from its
-// parent.
-- (void)removeOverlayCoordinator;
-
 @end
 
 #endif  // IOS_SHARED_CHROME_BROWSER_UI_COORDINATORS_BROWSER_COORDINATOR_INTERNAL_H_