[CRD iOS] Add the host setup instruction page

remoting/ios/app/host_collection_view_controller.mm

 // 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.
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #import "remoting/ios/app/host_collection_view_controller.h"
 
 #import "ios/third_party/material_components_ios/src/components/Ink/src/MaterialInk.h"
 #import "ios/third_party/material_components_ios/src/components/NavigationBar/src/MaterialNavigationBar.h"
 #import "ios/third_party/material_components_ios/src/components/ShadowElevations/src/MaterialShadowElevations.h"
 #import "ios/third_party/material_components_ios/src/components/ShadowLayer/src/MaterialShadowLayer.h"
 #import "remoting/ios/app/host_collection_header_view.h"
 
 static NSString* const kReusableIdentifierItem =
     @"remotingHostCollectionViewControllerItem";
 
 static CGFloat kHostCollectionViewControllerCellHeight = 70.f;
 static CGFloat kHostCollectionHeaderViewHeight = 25.f;
 
 @implementation HostCollectionViewController
 
 @synthesize delegate = _delegate;
-@synthesize flexHeaderContainerViewController =
-    _flexHeaderContainerViewController;
+@synthesize scrollViewDelegate = _scrollViewDelegate;
 
 - (instancetype)initWithCollectionViewLayout:(UICollectionViewLayout*)layout {
   self = [super initWithCollectionViewLayout:layout];
   if (self) {
     self.collectionView.backgroundColor = [UIColor clearColor];
     [self.collectionView registerClass:[HostCollectionViewCell class]
             forCellWithReuseIdentifier:NSStringFromClass(
                                            [HostCollectionViewCell class])];
 
     [self.collectionView registerClass:[HostCollectionHeaderView class]
@@ skipping 70 matching lines @@
 #pragma mark - MDCCollectionViewStylingDelegate
 
 - (CGFloat)collectionView:(UICollectionView*)collectionView
     cellHeightAtIndexPath:(NSIndexPath*)indexPath {
   return kHostCollectionViewControllerCellHeight;
 }
 
 #pragma mark - UIScrollViewDelegate
 
 - (void)scrollViewDidScroll:(UIScrollView*)scrollView {
-  [self.flexHeaderContainerViewController.headerViewController
-      scrollViewDidScroll:scrollView];
+  [_scrollViewDelegate scrollViewDidScroll:scrollView];
 }
 
 #pragma mark - UICollectionViewDelegateFlowLayout
 
 - (CGSize)collectionView:(UICollectionView*)collectionView
                              layout:
                                  (UICollectionViewLayout*)collectionViewLayout
     referenceSizeForHeaderInSection:(NSInteger)section {
   return CGSizeMake(collectionView.bounds.size.width,
                     kHostCollectionHeaderViewHeight);
 }
 
-#pragma mark - Private
-
-- (void)setFlexHeaderContainerViewController:
-    (MDCFlexibleHeaderContainerViewController*)
-        flexHeaderContainerViewController {
-  _flexHeaderContainerViewController = flexHeaderContainerViewController;
-  MDCFlexibleHeaderView* headerView =
-      _flexHeaderContainerViewController.headerViewController.headerView;
-  headerView.trackingScrollView = self.collectionView;
-  headerView.backgroundColor = [UIColor clearColor];
-
-  // Use a custom shadow under the flexible header.
-  MDCShadowLayer* shadowLayer = [MDCShadowLayer layer];
-  [headerView setShadowLayer:shadowLayer
-      intensityDidChangeBlock:^(CALayer* layer, CGFloat intensity) {
-        CGFloat elevation = MDCShadowElevationAppBar * intensity;
-        [(MDCShadowLayer*)layer setElevation:elevation];
-      }];
-}
-
 @end