Update to Chromium version 70.0.3538.0 (#587811)

Known issues:
- The CefLoadCRLSetsFile function needs to be re-implemented (see issue #2497).
- Linux: GTK2 support has been removed. The cefclient sample needs to be updated
  to use GTK3 (see issue #2014).

libcef/browser/net/crlset_file_util_impl.cc

@@ -19,7 +19,7 @@ namespace {
 
 void SetCRLSetIfNewer(scoped_refptr<net::CRLSet> crl_set) {
   CEF_REQUIRE_IOT();
-  net::SSLConfigService::SetCRLSetIfNewer(crl_set);
+  // TODO(cef): Re-implement via NetworkService.
 }
 
 void LoadFromDisk(const base::FilePath& path) {