[ios clean] Creates ToolbarWebState Mediator

ios/clean/chrome/browser/ui/toolbar/toolbar_web_state_mediator.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_CLEAN_CHROME_BROWSER_UI_TOOLBAR_TOOLBAR_WEB_STATE_MEDIATOR_H_
+#define IOS_CLEAN_CHROME_BROWSER_UI_TOOLBAR_TOOLBAR_WEB_STATE_MEDIATOR_H_
+
+#import <Foundation/Foundation.h>
+
+#import "ios/web/public/web_state/web_state_observer_bridge.h"
+
+@protocol ToolbarWebStateConsumer;
+
+namespace web {
+class WebState;
+}
+
+// A mediator object that provides the relevant properties of a web state
+// to a consumer.
+@interface ToolbarWebStateMediator : NSObject<CRWWebStateObserver>

[sczs, 2017/02/21 03:29:09]

Should we create a Mediator base class if this pattern is going to be used more
widely? 

[marq (ping after 24h), 2017/02/21 12:04:24]

There's no specific functionality of a Mediator (yet) that's worth encapsulating
in a base class, although it is good to keep an eye out for.

Please move the web_state_observer_bridge dependency and CRWWebStateObserver
protocol adoption into the .mm; they aren't part of the public API.

[sczs, 2017/02/21 17:28:28]

Done.

+
+// The WebState whose properties this object mediates. This can change during
+// the lifetime of this object and may be null.
+@property(nonatomic, assign) web::WebState* webState;
+
+// The consumer for this object. This can change during the lifetime of this
+// object and may be nil.
+@property(nonatomic, strong) id<ToolbarWebStateConsumer> consumer;
+
+@end
+
+#endif  // IOS_CLEAN_CHROME_BROWSER_UI_TOOLBAR_TOOLBAR_WEB_STATE_MEDIATOR_H_