This is failing because the restored URL isn't "about:blank" as expected, but rather the path to restore_session.html constructed in WKBasedNavigationManagerImpl::Restore. It looks like the way this is supposed t work is that loading restore_session.html actually restores the history rather than becoming part of the history. Maybe the test needs to wait longer for this to happen? Just waiting for |loading| to be false on |restored_web_view| isn't enough to make the test pass though.

Failure log:
../../ios/web_view/test/web_view_restorable_state_inttest.mm:59: Failure
      Expected: @"about:blank"
      Which is: about:blank
To be equal to: [restored_web_view lastCommittedURL].absoluteString
      Which is: (null)
../../ios/web_view/test/web_view_restorable_state_inttest.mm:60: Failure
      Expected: @"about:blank"
      Which is: about:blank
To be equal to: [restored_web_view visibleURL].absoluteString
      Which is: file:///Users/ajuma/Library/Developer/CoreSimulator/Devices/937C81D0-6D27-4F72-85B7-673682BD27EA/data/Containers/Bundle/Application/AD229AAB-BB0B-46FB-9130-15BEE0058278/ios_web_view_inttests.app/Frameworks/ChromeWebView.framework/restore_session.html?session=%7B%22offset%22%3A0%2C%22titles%22%3A%5B%22%22%2C%22%22%5D%2C%22urls%22%3A%5B%22about%3Anewtab%22%2C%22about%3Ablank%22%5D%7D