[ios] RootCoordinator and view controller.

ios/clean/chrome/browser/ui/root/root_coordinator.mm

+// Copyright 2017 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/clean/chrome/browser/ui/root/root_coordinator.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+#import "ios/clean/chrome/browser/ui/root/root_container_view_controller.h"
+#import "ios/clean/chrome/browser/ui/tab_grid/tab_grid_coordinator.h"
+#import "ios/shared/chrome/browser/ui/browser_list/browser.h"
+#import "ios/shared/chrome/browser/ui/coordinators/browser_coordinator+internal.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface RootCoordinator ()
+@property(nonatomic, strong) RootContainerViewController* viewController;
+@property(nonatomic, weak) TabGridCoordinator* tabGridCoordinator;
+@end
+
+@implementation RootCoordinator
+@synthesize viewController = _viewController;
+@synthesize tabGridCoordinator = _tabGridCoordinator;
+
+#pragma mark - BrowserCoordinator
+
+- (void)start {
+  self.viewController = [[RootContainerViewController alloc] init];
+
+  TabGridCoordinator* tabGridCoordinator = [[TabGridCoordinator alloc] init];
+  [self addChildCoordinator:tabGridCoordinator];
+  [tabGridCoordinator start];
+  self.tabGridCoordinator = tabGridCoordinator;
+
+  [super start];
+}
+
+- (void)stop {
+  [super stop];
+  // PLACEHOLDER: Stop child coordinators here for now. We might deal with this
+  // differently later on.
+  for (BrowserCoordinator* child in self.children) {
+    [child stop];
+    [self removeChildCoordinator:child];
+  }
+}
+
+- (void)childCoordinatorDidStart:(BrowserCoordinator*)childCoordinator {
+  self.viewController.contentViewController = childCoordinator.viewController;
+}
+
+- (void)childCoordinatorWillStop:(BrowserCoordinator*)childCoordinator {
+  self.viewController.contentViewController = nil;
+}
+
+- (BOOL)canAddOverlayCoordinator:(BrowserCoordinator*)overlayCoordinator {
+  return YES;
+}
+
+#pragma mark - URLOpening
+
+- (void)openURL:(NSURL*)URL {
+  [self.tabGridCoordinator openURL:URL];
+}
+
+@end