Seems to be due to an unexpected scheme:
[1457:8451:1031/101240.781596:1258043584795:FATAL:browser_about_rewriter.cc(35)] Check failed: (*url == url::kAboutBlankURL) || !url->SchemeIs(url::kAboutScheme).
0 ios_chrome_unittests 0x0000000108e6ec5d base::debug::StackTrace::StackTrace(unsigned long) + 157
1 ios_chrome_unittests 0x0000000108e6ec9d base::debug::StackTrace::StackTrace(unsigned long) + 29
2 ios_chrome_unittests 0x0000000108b4237a base::debug::StackTrace::StackTrace() + 26
3 ios_chrome_unittests 0x0000000108b8546d logging::LogMessage::~LogMessage() + 461
4 ios_chrome_unittests 0x0000000108b83115 logging::LogMessage::~LogMessage() + 21
5 ios_chrome_unittests 0x000000010764ab06 WillHandleWebBrowserAboutURL(GURL*, web::BrowserState*) + 646
6 ios_chrome_unittests 0x00000001077a2034 web::BrowserURLRewriter::RewriteURLWithWriters(GURL*, web::BrowserState*, std::__1::vector<bool ()(GURL, web::BrowserState*), std::__1::allocator<bool ()(GURL, web::BrowserState*)> > const&) + 420
7 ios_chrome_unittests 0x00000001077a2c19 web::BrowserURLRewriterImpl::RewriteURLIfNecessary(GURL*, web::BrowserState*) + 41
8 ios_chrome_unittests 0x00000001077d1988 web::NavigationManagerImpl::CreateNavigationItemWithRewriters(GURL const&, web::Referrer const&, ui::PageTransition, web::NavigationInitiationType, GURL const&, std::__1::vector<bool ()(GURL, web::BrowserState*), std::__1::allocator<bool ()(GURL, web::BrowserState*)> > const*) const + 376
9 ios_chrome_unittests 0x00000001078fcdf3 web::WKBasedNavigationManagerImpl::AddPendingItem(GURL const&, web::Referrer const&, ui::PageTransition, web::NavigationInitiationType, web::NavigationManager::UserAgentOverrideOption) + 323
10 ios_chrome_unittests 0x00000001077d2a9d web::NavigationManagerImpl::LoadURLWithParams(web::NavigationManager::WebLoadParams const&) + 429
11 ios_chrome_unittests 0x0000000108222bd2 web::WebTestWithWebState::LoadHtml(NSString*, GURL const&) + 1042
12 ios_chrome_unittests 0x00000001082242cc web::WebTestWithWebState::LoadHtml(NSString*) + 124
Comment 1 by bugdroid1@chromium.org
, Oct 31