[ios clean] Consumer interface for WebContents

ios/clean/chrome/browser/ui/web_contents/web_coordinator.mm

 // Copyright 2016 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.
 
 // ======                        New Architecture                         =====
 // =         This code is only used in the new iOS Chrome architecture.       =
 // ============================================================================
 
 #import "ios/clean/chrome/browser/ui/web_contents/web_coordinator.h"
 
 #import "ios/clean/chrome/browser/browser_coordinator+internal.h"
+#import "ios/clean/chrome/browser/ui/web_contents/web_contents_mediator.h"
 #import "ios/clean/chrome/browser/ui/web_contents/web_contents_view_controller.h"
 #import "ios/shared/chrome/browser/coordinator_context/coordinator_context.h"
 #include "ios/web/public/web_state/web_state.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 @interface WebCoordinator ()
-
 @property(nonatomic, strong) WebContentsViewController* viewController;
-
+@property(nonatomic, strong) WebContentsMediator* mediator;
 @end
 
 @implementation WebCoordinator
 @synthesize webState = _webState;
 @synthesize viewController = _viewController;
+@synthesize mediator = _mediator;
+
+- (instancetype)init {
+  if ((self = [super init])) {
+    _mediator = [[WebContentsMediator alloc] init];
+  }
+  return self;
+}
+
+- (void)setWebState:(web::WebState*)webState {
+  _webState = webState;
+  self.mediator.webState = self.webState;
+}
 
 - (void)start {
-  self.webState->SetWebUsageEnabled(true);
-  self.viewController =
-      [[WebContentsViewController alloc] initWithWebState:self.webState];
+  self.viewController = [[WebContentsViewController alloc] init];
+  self.mediator.consumer = self.viewController;
 
   // Reminder: this is a no-op if |baseViewController| is nil, for example
   // when this coordinator's view controller will be contained instead of
   // presented.
   [self.context.baseViewController presentViewController:self.viewController
                                                 animated:self.context.animated
                                               completion:nil];
 }
 
 - (void)stop {
-  self.webState->SetWebUsageEnabled(false);
+  // PLACEHOLDER: This is how the webUsageEnabled is set to false. Find a
+  // better way in the future.
+  self.mediator.webState = nullptr;
 }
 
 @end