Remove CWV class and move setting User Agent to CWVWebViewConfiguration.

ios/web_view/public/cwv_web_view_configuration.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_WEB_VIEW_CONFIGURATION_H_
 #define IOS_WEB_VIEW_PUBLIC_CWV_WEB_VIEW_CONFIGURATION_H_
 
 #import <ChromeWebView/cwv_export.h>
 #import <Foundation/Foundation.h>
 
 @class CWVUserContentController;
 @class CWVWebsiteDataStore;
 
 // Configuration used for creation of a CWVWebView.
 CWV_EXPORT
 @interface CWVWebViewConfiguration : NSObject<NSCopying>
 
 // Configuration with persistent data store which stores all data on disk.
 + (instancetype)defaultConfiguration;
 
 // Configuration with ephemeral data store that neven stores data on disk.
 + (instancetype)incognitoConfiguration;
 
 - (instancetype)init NS_UNAVAILABLE;
 
+// Customizes the User Agent string used by web views. It should be of the
+// format "product/1.0". NOTE: This must be called before any

[Eugene But (OOO till 7-30), 2017/04/04 21:50:26]

This is pretty strict requirement. Is it temporary? Or so, please add a TODO. I
think we should avoid API that "must be called" before anything else.

[michaeldo, 2017/04/07 22:31:35]

Moved to CWVWebView as static method per discussion. Added better comment there
as well.

+// CWVWebViewConfiguration is initialized.
++ (void)setUserAgentProductName:(NSString*)userAgent;
+
 // The user content controller to associate with web views created using this
 // configuration.
 @property(nonatomic, readonly) CWVUserContentController* userContentController;
 
 // YES if it is a configuration with persistent data store which stores all data
 // on disk.
 @property(nonatomic, readonly, getter=isPersistent) BOOL persistent;
 
 @end
 
 #endif  // IOS_WEB_VIEW_PUBLIC_CWV_WEB_VIEW_CONFIGURATION_H_