[Clean Skeleton] Migrate code to clean/

ios/chrome/browser/browser_coordinator.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.
-
-// ======                        New Architecture                         =====
-// =         This code is only used in the new iOS Chrome architecture.       =
-// ============================================================================
-
-#import "base/logging.h"
-#import "ios/chrome/browser/browser_coordinator+internal.h"
-#import "ios/chrome/browser/browser_coordinator.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
-
-@interface BrowserCoordinator ()
-// Child coordinators owned by this object.
-@property(nonatomic, strong)
-    NSMutableSet<BrowserCoordinator*>* childCoordinators;
-// Parent coordinator of this object, if any.
-@property(nonatomic, readwrite, weak) BrowserCoordinator* parentCoordinator;
-@property(nonatomic, readwrite) BOOL overlaying;
-@end
-
-@implementation BrowserCoordinator
-
-@synthesize browserState = _browserState;
-@synthesize rootViewController = _rootViewController;
-@synthesize childCoordinators = _childCoordinators;
-@synthesize parentCoordinator = _parentCoordinator;
-@synthesize overlaying = _overlaying;
-
-- (instancetype)init {
-  if (self = [super init]) {
-    _childCoordinators = [NSMutableSet set];
-  }
-  return self;
-}
-
-- (void)dealloc {
-  [self stop];
-}
-
-#pragma mark - Public API
-
-- (void)start {
-  // Default implementation is a no-op.
-}
-
-- (void)stop {
-  // Default implementation is a no-op.
-}
-
-@end
-
-@implementation BrowserCoordinator (Internal)
-// Concrete implementations must implement a |viewController| property.
-@dynamic viewController;
-
-- (NSSet*)children {
-  return [self.childCoordinators copy];
-}
-
-- (void)addChildCoordinator:(BrowserCoordinator*)coordinator {
-  [self.childCoordinators addObject:coordinator];
-  coordinator.browserState = self.browserState;
-  coordinator.parentCoordinator = self;
-  coordinator.rootViewController = self.viewController;
-}
-
-- (BrowserCoordinator*)overlayCoordinator {
-  if (self.overlaying)
-    return self;
-  for (BrowserCoordinator* child in self.children) {
-    BrowserCoordinator* overlay = child.overlayCoordinator;
-    if (overlay)
-      return overlay;
-  }
-  return nil;
-}
-
-- (void)addOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator {
-  // If this object has no children, then add |overlayCoordinator| as a child
-  // and mark it as such.
-  if ([self canAddOverlayCoordinator:overlayCoordinator]) {
-    [self addChildCoordinator:overlayCoordinator];
-    overlayCoordinator.overlaying = YES;
-  } else if (self.childCoordinators.count == 1) {
-    [[self.childCoordinators anyObject]
-        addOverlayCoordinator:overlayCoordinator];
-  } else {
-    CHECK(NO) << "Coordinators with multiple children must explicitly "
-              << "handle -addOverlayCoordinator: or return NO to "
-              << "-canAddOverlayCoordinator:";
-  }
-}
-
-- (void)removeOverlayCoordinator {
-  BrowserCoordinator* overlay = self.overlayCoordinator;
-  [overlay.parentCoordinator removeChildCoordinator:overlay];
-}
-
-- (BOOL)canAddOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator {
-  // By default, coordinators with no other children can add an overlay.
-  return self.childCoordinators.count == 0;
-}
-
-- (void)removeChildCoordinator:(BrowserCoordinator*)coordinator {
-  [self.childCoordinators removeObject:coordinator];
-}
-
-@end