[iOS] Adding APIs to support multiwindow with SSO

Adding APIs declaration to support multi windows with SSO.

For ChromeIdentityService:
bool HandleSessionOpenURLContexts(UIScene* scene, NSSet*)
void ApplicationDidDiscardSceneSessions(NSSet*)


=> crrev.com/c/2316308 API declarations
 * crrev.com/i/3182384 Implementing APIs
 * crrev.com/c/2317321 Switching code to use the new APIs

Bug: 1103833
Change-Id: I28b5f6c98c23d9c1424500816bf713756bab4c05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316308Reviewed-by: Nohemi Fernandez <fernandex@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Auto-Submit: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#792196}

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

@@ -26,6 +26,7 @@ class ChromeBrowserState;
 @class UIApplication;
 @class UIImage;
 @class UINavigationController;
+@class UIScene;
 @class UIViewController;
 
 namespace ios {
@@ -102,11 +103,22 @@ class ChromeIdentityService {
 
   // Handles open URL authentication callback. Returns whether the URL was
   // actually handled. This should be called within
-  // UIApplicationDelegate application:openURL:options:.
+  // -[<UIApplicationDelegate> application:openURL:options:].
   virtual bool HandleApplicationOpenURL(UIApplication* application,
                                         NSURL* url,
                                         NSDictionary* options);
 
+  // Handles open URL authentication callback. Returns whether the URL was
+  // actually handled. This should be called within
+  // -[<UISceneDelegate> application:openURLContexts:].
+  virtual bool HandleSessionOpenURLContexts(UIScene* scene, NSSet* url_contexts)
+      API_AVAILABLE(ios(13.0));
+
+  // Discards scene session data.This should be called within
+  // -[<UIApplicationDelegate> application:didDiscardSceneSessions:].
+  virtual void ApplicationDidDiscardSceneSessions(NSSet* scene_sessions)
+      API_AVAILABLE(ios(13.0));
+
   // Dismisses all the dialogs created by the abstracted flows.
   virtual void DismissDialogs();
 

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

@@ -30,6 +30,14 @@ bool ChromeIdentityService::HandleApplicationOpenURL(UIApplication* application,
   return false;
 }
 
+bool ChromeIdentityService::HandleSessionOpenURLContexts(UIScene* scene,
+                                                         NSSet* URLContexts) {
+  return false;
+}
+
+void ChromeIdentityService::ApplicationDidDiscardSceneSessions(
+    NSSet* scene_sessions) {}
+
 DismissASMViewControllerBlock
 ChromeIdentityService::PresentAccountDetailsController(
     ChromeIdentity* identity,