Add CWVUserContentController which enables injecting JavaScripts.

ios/web_view/public/cwv_user_script.h

Index: ios/web_view/public/cwv_user_script.h
diff --git a/ios/web_view/public/cwv_user_script.h b/ios/web_view/public/cwv_user_script.h
new file mode 100644
index 0000000000000000000000000000000000000000..e7bb81dfd1dfb4004536e1688ab09bf4e3c8ca4e
--- /dev/null
+++ b/ios/web_view/public/cwv_user_script.h
@@ -0,0 +1,25 @@
+// Copyright 2017 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.
+#ifndef IOS_WEB_VIEW_PUBLIC_CWV_USER_SCRIPT_H_
+#define IOS_WEB_VIEW_PUBLIC_CWV_USER_SCRIPT_H_
+
+#import <Foundation/Foundation.h>
+
+// User Script to be injected into main frame of CWVWebView after
+// window.document is created, but before other content is
+// loaded (i.e., at the same timing as

[michaeldo, 2017/03/21 16:12:35]

please re-wrap this comment

[Hiroshi Ichikawa, 2017/03/22 04:52:53]

Done.

+// WKUserScriptInjectionTimeAtDocumentStart).
+__attribute__((visibility("default")))

[michaeldo, 2017/03/21 16:12:35]

I think we shuold remove the visibility attribute for now. It is missing from
most of the other classes, and if we want to add them to all the classes, we
should do that in a separate CL. If you want to add it here since this is a new
header, please add to cwv_user_content_controller.h as well.

[Hiroshi Ichikawa, 2017/03/22 04:52:53]

Sure. Reverted. I added this here because my test code using this this feature
didn't work without this attribute.

[michaeldo, 2017/03/22 23:03:33]

Understandable, thank you for creating the separate CL.

+@interface CWVUserScript : NSObject
+
+// JavaScript source code.
+@property(copy, readonly) NSString* source;

[michaeldo, 2017/03/21 16:12:35]

Please add nullability annotations to this newly created header.

[Eugene But (OOO till 7-30), 2017/03/21 16:47:55]

nonatomic?

[Hiroshi Ichikawa, 2017/03/22 04:52:53]

Done.

[Hiroshi Ichikawa, 2017/03/22 04:52:53]

Done.

+
+- (instancetype)init NS_UNAVAILABLE;
+
+- (instancetype)initWithSource:(NSString*)source;

[Eugene But (OOO till 7-30), 2017/03/21 16:47:55]

Do you want to add nonnull to |source|?

[Hiroshi Ichikawa, 2017/03/22 04:52:53]

Done.

+
+@end
+
+#endif  // IOS_WEB_VIEW_PUBLIC_CWV_USER_SCRIPT_H_