Coordinators are now notified when moving to a parent coordinator.

ios/clean/chrome/browser/browser_coordinator.mm

Index: ios/clean/chrome/browser/browser_coordinator.mm
diff --git a/ios/clean/chrome/browser/browser_coordinator.mm b/ios/clean/chrome/browser/browser_coordinator.mm
index 828ae8d4f6c66cd4e69feb3565c4e17be8c95f16..9cb877691485270dff040b30e54e4797cb849154 100644
--- a/ios/clean/chrome/browser/browser_coordinator.mm
+++ b/ios/clean/chrome/browser/browser_coordinator.mm
@@ -68,6 +68,7 @@
   coordinator.parentCoordinator = self;
   coordinator.browser = self.browser;
   coordinator.context.baseViewController = self.viewController;
+  [coordinator coordinatorDidMoveToParentCoordinator];
 }
 
 - (BrowserCoordinator*)overlayCoordinator {
@@ -122,6 +123,10 @@
   coordinator.parentCoordinator = nil;
 }
 
+- (void)coordinatorDidMoveToParentCoordinator {
+  // Default implementation is a no-op.
+}
+
 - (void)childCoordinatorDidStart:(BrowserCoordinator*)childCoordinator {
   // Default implementation is a no-op.
 }