[ios] Allow having multiple session windows in a session.

ios/chrome/browser/sessions/test_session_service.mm

Index: ios/chrome/browser/sessions/test_session_service.mm
diff --git a/ios/chrome/browser/sessions/test_session_service.mm b/ios/chrome/browser/sessions/test_session_service.mm
index cd2566790e12716b7cfdcb73736dbf4cfd14b679..34f61ede568307c17594954dabf9b54475a01e61 100644
--- a/ios/chrome/browser/sessions/test_session_service.mm
+++ b/ios/chrome/browser/sessions/test_session_service.mm
@@ -19,11 +19,11 @@
   return [super initWithTaskRunner:base::ThreadTaskRunnerHandle::Get()];
 }
 
-- (void)saveSessionWindow:(SessionWindowIOS*)sessionWindow
-                directory:(NSString*)directory
-              immediately:(BOOL)immediately {
+- (void)saveSession:(SessionIOS*)session
+          directory:(NSString*)directory
+        immediately:(BOOL)immediately {
   NSString* sessionPath = [[self class] sessionPathForDirectory:directory];
-  NSData* data = [NSKeyedArchiver archivedDataWithRootObject:sessionWindow];
+  NSData* data = [NSKeyedArchiver archivedDataWithRootObject:session];
   if (self.performIO)
     [self performSaveSessionData:data sessionPath:sessionPath];
 }