Don't save or load cookies for non-cookieable scheme requests.

This fixes an IsCanonical() DCHECK failure triggered by calling
CanonicalCookie::Create for a non-cookieable URL.

This change also adds unit test coverage for cross-origin cookie
behavior with sub-resource requests (iframe, XHR, Fetch).

libcef/browser/alloy/alloy_browser_context.h

@@ -103,7 +103,7 @@ class AlloyBrowserContext : public ChromeProfileAlloy,
     return !!settings_.persist_session_cookies;
   }
   base::Optional<std::vector<std::string>> GetCookieableSchemes() override {
-    return cookieable_schemes_;
+    return cookieable_schemes();
   }
 
   // visitedlink::VisitedLinkDelegate methods.