Cleanup and add NOTREACHED to supplementaryView method.

ios/chrome/browser/ui/ntp/google_landing_controller.mm

 // Copyright 2013 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.
 
 #import "ios/chrome/browser/ui/ntp/google_landing_controller.h"
 
 #include <algorithm>
 
 #include "base/i18n/case_conversion.h"
 #import "base/ios/weak_nsobject.h"
@@ skipping 1205 matching lines @@
                referrer:web::Referrer()
              transition:ui::PAGE_TRANSITION_AUTO_BOOKMARK
       rendererInitiated:NO];
 }
 
 #pragma mark - UICollectionViewDataSource
 
 - (UICollectionReusableView*)collectionView:(UICollectionView*)collectionView
           viewForSupplementaryElementOfKind:(NSString*)kind
                                 atIndexPath:(NSIndexPath*)indexPath {
+  DCHECK(kind == UICollectionElementKindSectionHeader);
+
   if (!_supplementaryViews)
     _supplementaryViews.reset([[NSMutableArray alloc] init]);
-  if (kind == UICollectionElementKindSectionHeader) {
-    NSUInteger section = indexPath.section;
-    if (section == SectionWithOmnibox) {
-      if (!_headerView) {
-        _headerView.reset([[collectionView
-            dequeueReusableSupplementaryViewOfKind:
-                UICollectionElementKindSectionHeader
-                               withReuseIdentifier:@"header"
-                                      forIndexPath:indexPath] retain]);
-        [_headerView addSubview:[_doodleController view]];
-        [_headerView addSubview:_searchTapTarget];
-        [_headerView addViewsToSearchField:_searchTapTarget];
 
-        if (!IsIPadIdiom()) {
-          ReadingListModel* readingListModel = nullptr;
-          if (reading_list::switches::IsReadingListEnabled()) {
-            readingListModel =
-                ReadingListModelFactory::GetForBrowserState(_browserState);
-          }
-          // iPhone header also contains a toolbar since the normal toolbar is
-          // hidden.
-          [_headerView addToolbarWithDelegate:_webToolbarDelegate
-                                      focuser:_focuser
-                                     tabModel:_tabModel
-                             readingListModel:readingListModel];
+  if (indexPath.section == SectionWithOmnibox) {
+    if (!_headerView) {
+      _headerView.reset([[collectionView
+          dequeueReusableSupplementaryViewOfKind:
+              UICollectionElementKindSectionHeader
+                             withReuseIdentifier:@"header"
+                                    forIndexPath:indexPath] retain]);
+      [_headerView addSubview:[_doodleController view]];
+      [_headerView addSubview:_searchTapTarget];
+      [_headerView addViewsToSearchField:_searchTapTarget];
+
+      if (!IsIPadIdiom()) {
+        ReadingListModel* readingListModel = nullptr;
+        if (reading_list::switches::IsReadingListEnabled()) {
+          readingListModel =
+              ReadingListModelFactory::GetForBrowserState(_browserState);
         }
-        [_supplementaryViews addObject:_headerView];
+        // iPhone header also contains a toolbar since the normal toolbar is
+        // hidden.
+        [_headerView addToolbarWithDelegate:_webToolbarDelegate
+                                    focuser:_focuser
+                                   tabModel:_tabModel
+                           readingListModel:readingListModel];
       }
-      return _headerView;
-    } else if (section == SectionWithMostVisited) {
-      if (!_promoHeaderView) {
-        _promoHeaderView.reset([[collectionView
-            dequeueReusableSupplementaryViewOfKind:
-                UICollectionElementKindSectionHeader
-                               withReuseIdentifier:@"whatsNew"
-                                      forIndexPath:indexPath] retain]);
-        [_promoHeaderView setSideMargin:[self leftMargin]];
-        [_promoHeaderView setDelegate:self];
-        if (_notification_promo && _notification_promo->CanShow()) {
-          [_promoHeaderView setText:base::SysUTF8ToNSString(
-                                        _notification_promo->promo_text())];
-          [_promoHeaderView setIcon:_notification_promo->icon()];
-          _notification_promo->HandleViewed();
-        }
-        [_supplementaryViews addObject:_promoHeaderView];
+      [_supplementaryViews addObject:_headerView];
+    }
+    return _headerView;
+  }
+
+  if (indexPath.section == SectionWithMostVisited) {
+    if (!_promoHeaderView) {
+      _promoHeaderView.reset([[collectionView
+          dequeueReusableSupplementaryViewOfKind:
+              UICollectionElementKindSectionHeader
+                             withReuseIdentifier:@"whatsNew"
+                                    forIndexPath:indexPath] retain]);
+      [_promoHeaderView setSideMargin:[self leftMargin]];
+      [_promoHeaderView setDelegate:self];
+      if (_notification_promo && _notification_promo->CanShow()) {
+        [_promoHeaderView
+            setText:base::SysUTF8ToNSString(_notification_promo->promo_text())];
+        [_promoHeaderView setIcon:_notification_promo->icon()];
+        _notification_promo->HandleViewed();
       }
-      return _promoHeaderView;
+      [_supplementaryViews addObject:_promoHeaderView];
     }
+    return _promoHeaderView;
   }
+
+  NOTREACHED();
   return nil;
 }
 
 - (NSInteger)numberOfSectionsInCollectionView:
     (UICollectionView*)collectionView {
   return NumberOfCollectionViewSections;
 }
 
 - (NSInteger)collectionView:(UICollectionView*)collectionView
      numberOfItemsInSection:(NSInteger)section {
@@ skipping 453 matching lines @@
   if (!view) {
     return nil;
   }
   if ([view isKindOfClass:aClass]) {
     return view;
   }
   return [self nearestAncestorOfView:[view superview] withClass:aClass];
 }
 
 @end