Add script to generate CronetChromeWebView.framework

ios/web_view/public/cwv_user_script.h

 // 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 <ChromeWebView/cwv_export.h>
 #import <Foundation/Foundation.h>
 
+#import "cwv_export.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 WKUserScriptInjectionTimeAtDocumentStart).
 CWV_EXPORT
 @interface CWVUserScript : NSObject
 
 // JavaScript source code.
 @property(nonatomic, copy, readonly, nonnull) NSString* source;
 
 - (nonnull instancetype)init NS_UNAVAILABLE;
 
 - (nonnull instancetype)initWithSource:(nonnull NSString*)source;
 
 @end
 
 #endif  // IOS_WEB_VIEW_PUBLIC_CWV_USER_SCRIPT_H_