Removes usage of signin APIs that return scoped_nsobjects.

ios/public/provider/chrome/browser/signin/chrome_identity_service.mm

Index: ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
diff --git a/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm b/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
index e19e1eee4c25a73442f3d8f918f4a9fc412b5ec4..c2e347eba433ba36fa428ece3d6c227f5dc6f808 100644
--- a/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
+++ b/ios/public/provider/chrome/browser/signin/chrome_identity_service.mm
@@ -23,25 +23,24 @@ bool ChromeIdentityService::HandleApplicationOpenURL(UIApplication* application,
   return false;
 }
 
-base::scoped_nsobject<UINavigationController>
-ChromeIdentityService::NewAccountDetails(
+UINavigationController* ChromeIdentityService::CreateAccountDetailsController(
     ChromeIdentity* identity,
     id<ChromeIdentityBrowserOpener> browser_opener) {
-  return base::scoped_nsobject<UINavigationController>();
+  return nil;
 }
 
-base::scoped_nsobject<UINavigationController>
-ChromeIdentityService::NewWebAndAppSettingDetails(
+UINavigationController*
+ChromeIdentityService::CreateWebAndAppSettingDetailsController(
     ChromeIdentity* identity,
     id<ChromeIdentityBrowserOpener> browser_opener) {
-  return base::scoped_nsobject<UINavigationController>();
+  return nil;
 }
 
-base::scoped_nsobject<ChromeIdentityInteractionManager>
-ChromeIdentityService::NewChromeIdentityInteractionManager(
+ChromeIdentityInteractionManager*
+ChromeIdentityService::CreateChromeIdentityInteractionManager(
     ios::ChromeBrowserState* browser_state,
     id<ChromeIdentityInteractionManagerDelegate> delegate) const {
-  return base::scoped_nsobject<ChromeIdentityInteractionManager>();
+  return nil;
 }
 
 bool ChromeIdentityService::IsValidIdentity(ChromeIdentity* identity) const {