[ios clean] Consumer interface for WebContents

ios/clean/chrome/browser/ui/web_contents/web_contents_view_controller.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_contents_view_controller.h"
 
-#import "ios/web/public/navigation_manager.h"
-#include "ios/web/public/web_state/web_state.h"
-#include "ui/base/page_transition_types.h"
-#include "url/gurl.h"
-
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
+@interface WebContentsViewController ()
+@property(nonatomic, strong) UIView* contentView;
+@end
+
 @implementation WebContentsViewController
 
-@synthesize webState = _webState;
-
-- (instancetype)initWithWebState:(web::WebState*)webState {
-  if ((self = [super initWithNibName:nil bundle:nil])) {
-    DCHECK(webState);
-    _webState = webState;
-  }
-  return self;
-}
+@synthesize contentView = _contentView;
 
 - (void)viewDidLoad {
   self.view.backgroundColor = [UIColor colorWithWhite:0.75 alpha:1.0];
 
-  UIView* webContentsView = self.webState->GetView();
-  webContentsView.translatesAutoresizingMaskIntoConstraints = NO;
-  [self.view addSubview:webContentsView];
-  [NSLayoutConstraint activateConstraints:@[
-    [webContentsView.topAnchor constraintEqualToAnchor:self.view.topAnchor],
-    [webContentsView.bottomAnchor
-        constraintEqualToAnchor:self.view.bottomAnchor],
-    [webContentsView.leadingAnchor
-        constraintEqualToAnchor:self.view.leadingAnchor],
-    [webContentsView.trailingAnchor
-        constraintEqualToAnchor:self.view.trailingAnchor],
-  ]];
+  [self updateContentView];
+}
 
-  if (!self.webState->GetNavigationManager()->GetItemCount()) {
-    web::NavigationManager::WebLoadParams params(
-        GURL("https://dev.chromium.org/"));
-    params.transition_type = ui::PAGE_TRANSITION_TYPED;
-    _webState->GetNavigationManager()->LoadURLWithParams(params);
-  }
+#pragma mark - WebContentsConsumer
+
+- (void)contentViewDidChange:(UIView*)contentView {
+  if (contentView == self.contentView)
+    return;
+
+  // If there was a previous content view, remove it from the view hierarchy.
+  [self.contentView removeFromSuperview];
+  self.contentView = contentView;
+
+  // If self.view hasn't loaded yet, this call shouldn't induce that load.
+  // (calling self.view will trigger -loadView, etc.). Only update for the
+  // new content view if there's a view to update.
+  if (self.viewIfLoaded)
+    [self updateContentView];
+}
+
+#pragma mark - Private methods
+
+- (void)updateContentView {
+  self.contentView.frame = self.view.bounds;
+  self.contentView.autoresizingMask =
+      UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+  [self.view addSubview:self.contentView];
 }
 
 @end