Upstream ChromeBrowserState sub-classes.

ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.mm

Index: ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.mm
diff --git a/ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.mm b/ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.mm
new file mode 100644
index 0000000000000000000000000000000000000000..ad97ae0c1ae3557b7ce4af9745c7590d967304dc
--- /dev/null
+++ b/ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.mm
@@ -0,0 +1,30 @@
+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/public/provider/chrome/browser/ui/default_ios_web_view_factory.h"
+
+#include "base/logging.h"
+
+namespace {
+Class g_registered_factory_class = nil;
+}  // namespace
+
+@implementation DefaultIOSWebViewFactory
+
++ (void)registerWebViewFactory:(Class)webViewFactoryClass {
+  DCHECK([webViewFactoryClass conformsToProtocol:@protocol(IOSWebViewFactory)]);
+  g_registered_factory_class = webViewFactoryClass;
+}
+
+#pragma mark -
+#pragma mark IOSWebViewFactory
+
++ (UIWebView*)
+    newExternalWebView:(IOSWebViewFactoryExternalService)externalService {
+  if (g_registered_factory_class)
+    return [g_registered_factory_class newExternalWebView:externalService];
+  return [[UIWebView alloc] init];
+}
+
+@end