Upstream JavaScript injection for iOS

ios/web/web_state/js/crw_js_base_manager.mm

Index: ios/web/web_state/js/crw_js_base_manager.mm
diff --git a/ios/web/web_state/js/crw_js_base_manager.mm b/ios/web/web_state/js/crw_js_base_manager.mm
new file mode 100644
index 0000000000000000000000000000000000000000..29507bcc963dcd89a7931317cb5fb055801bd921
--- /dev/null
+++ b/ios/web/web_state/js/crw_js_base_manager.mm
@@ -0,0 +1,20 @@
+// Copyright 2013 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/web/public/web_state/js/crw_js_base_manager.h"
+
+@implementation CRWJSBaseManager
+
+#pragma mark -
+#pragma mark ProtectedMethods
+
+- (NSString*)scriptPath {
+  return @"base";
+}
+
+- (NSString*)presenceBeacon {
+  return @"__gCrWeb";
+}
+
+@end