Upstream JavaScript injection for iOS

ios/web/web_state/js/crw_js_message_manager.mm

Index: ios/web/web_state/js/crw_js_message_manager.mm
diff --git a/ios/web/web_state/js/crw_js_message_manager.mm b/ios/web/web_state/js/crw_js_message_manager.mm
new file mode 100644
index 0000000000000000000000000000000000000000..59fd57d9156892c03246a551301e23f765cde673
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+++ b/ios/web/web_state/js/crw_js_message_manager.mm
@@ -0,0 +1,25 @@
+// Copyright 2014 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_message_manager.h"
+
+#import "ios/web/web_state/js/crw_js_common_manager.h"
+#import "ios/web/web_state/js/crw_js_message_dynamic_manager.h"
+
+@implementation CRWJSMessageManager
+
+- (NSString*)scriptPath {
+  return @"message";
+}
+
+- (NSString*)presenceBeacon {
+  return @"__gCrWeb.message";
+}
+
+- (NSArray*)directDependencies {
+  // The 'base' manager is omitted deliberately; see <crbug.com/404640>.
+  return @[ [CRWJSCommonManager class], [CRWJSMessageDynamicManager class] ];
+}
+
+@end