[ios] Fixes History CollectionVC top margin.

Before crrev.com/c/695934, a top message was always being displayed.
Now thats not the case, this CLremoves the top cell that contains the message if there's no message.

Also, on iOS11 the contentInset was being adjusted automatically, causing an even larger
blank space on top. This is fixed by setting the ContentInsetAdjustmentBehavior to never.

Screenshots:
https://drive.google.com/open?id=1N6egGvEOeSF2uags3w4hmLupWy7Vk4v3
https://drive.google.com/open?id=1hCW15FIUtw2o5rJ7MiqDcRd1z6Xq42O0

Bug: 778571
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I2b9f2b5f92e22f955fb10c5ea609f4ee4f130836
Reviewed-on: https://chromium-review.googlesource.com/830911
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Reviewed-by: Louis Romero <lpromero@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524588}

ios/chrome/browser/ui/history/history_collection_view_controller.mm

@@ -203,6 +203,13 @@ const CGFloat kSeparatorInset = 10;
       UIEdgeInsetsMake(0, kSeparatorInset, 0, kSeparatorInset);
   self.styler.allowsItemInlay = NO;
 
+  // Never adjust the content inset on iOS11 or it will create padding on top of
+  // the first cell.
+  if (@available(iOS 11, *)) {
+    [self.collectionView setContentInsetAdjustmentBehavior:
+                             UIScrollViewContentInsetAdjustmentNever];
+  }
+
   self.clearsSelectionOnViewWillAppear = NO;
   self.collectionView.keyboardDismissMode =
       UIScrollViewKeyboardDismissModeOnDrag;
@@ -645,21 +652,20 @@ const CGFloat kSeparatorInset = 10;
         self.isSearching ? l10n_util::GetNSString(IDS_HISTORY_NO_SEARCH_RESULTS)
                          : l10n_util::GetNSString(IDS_HISTORY_NO_RESULTS);
     entriesStatusItem = noResultsItem;
-  } else {
+  } else if (self.shouldShowNoticeAboutOtherFormsOfBrowsingHistory) {
     HistoryEntriesStatusItem* historyEntriesStatusItem =
         [[HistoryEntriesStatusItem alloc] initWithType:ItemTypeEntriesStatus];
     historyEntriesStatusItem.delegate = self;
     historyEntriesStatusItem.hidden = self.isSearching;
-    historyEntriesStatusItem.showsOtherBrowsingDataNotice =
-        _shouldShowNoticeAboutOtherFormsOfBrowsingHistory;
     entriesStatusItem = historyEntriesStatusItem;
   }
-  // Replace the item in the first section, which is always present.
+  // Replace the item in the first section if it exists. Then insert the new
+  // item if it exists.
   NSArray* items = [self.collectionViewModel
       itemsInSectionWithIdentifier:kEntriesStatusSectionIdentifier];
   if ([items count]) {
-    // There should only ever be one item in this section.
-    DCHECK([items count] == 1);
+    // There should only ever be at most one item in this section.
+    DCHECK([items count] <= 1);
     // Only update if the item has changed.
     if ([items[0] isEqual:entriesStatusItem]) {
       return;
@@ -674,9 +680,11 @@ const CGFloat kSeparatorInset = 10;
           fromSectionWithIdentifier:kEntriesStatusSectionIdentifier];
       [self.collectionView deleteItemsAtIndexPaths:@[ indexPath ]];
     }
+    if (entriesStatusItem) {
       [self.collectionViewModel addItem:entriesStatusItem
                 toSectionWithIdentifier:kEntriesStatusSectionIdentifier];
       [self.collectionView insertItemsAtIndexPaths:@[ indexPath ]];
+    }
   }
                                 completion:nil];
 }

ios/chrome/browser/ui/history/history_collection_view_controller_unittest.mm

@@ -160,9 +160,8 @@ TEST_F(HistoryCollectionViewControllerTest, DeleteSingleEntry) {
              scrollPosition:UICollectionViewScrollPositionNone];
   [history_collection_view_controller_ deleteSelectedItemsFromHistory];
 
-  // Expect header section with one item and one entries section with one item.
+  // Expect header section and one entries section with one item.
   EXPECT_EQ(2, [collection_view numberOfSections]);
-  EXPECT_EQ(1, [collection_view numberOfItemsInSection:0]);
   EXPECT_EQ(1, [collection_view numberOfItemsInSection:1]);
 }
 
@@ -189,7 +188,6 @@ TEST_F(HistoryCollectionViewControllerTest, DeleteMultipleEntries) {
 
   // Expect only the header section to remain.
   EXPECT_EQ(1, [collection_view numberOfSections]);
-  EXPECT_EQ(1, [collection_view numberOfItemsInSection:0]);
 }
 
 // Tests that adding two entries to history from different days then deleting
@@ -217,5 +215,4 @@ TEST_F(HistoryCollectionViewControllerTest, DeleteMultipleSections) {
 
   // Expect only the header section to remain.
   EXPECT_EQ(1, [collection_view numberOfSections]);
-  EXPECT_EQ(1, [collection_view numberOfItemsInSection:0]);
 }

ios/chrome/browser/ui/history/history_entries_status_item.h

@@ -25,8 +25,6 @@ class GURL;
 @interface HistoryEntriesStatusItem : CollectionViewItem
 // YES if messages should be hidden.
 @property(nonatomic, assign, getter=isHidden) BOOL hidden;
-// YES if message for other forms of browsing data should be shown.
-@property(nonatomic, assign) BOOL showsOtherBrowsingDataNotice;
 // Delegate for HistoryEntriesStatusItem. Is notified when a link is pressed.
 @property(nonatomic, weak) id<HistoryEntriesStatusItemDelegate> delegate;
 @end

ios/chrome/browser/ui/history/history_entries_status_item.mm

@@ -44,16 +44,6 @@
 @implementation HistoryEntriesStatusItem
 @synthesize delegate = _delegate;
 @synthesize hidden = _hidden;
-@synthesize showsOtherBrowsingDataNotice = _showsOtherBrowsingDataNotice;
-
-- (instancetype)initWithType:(NSInteger)type {
-  self = [super initWithType:type];
-  if (self) {
-    _hidden = NO;
-    _showsOtherBrowsingDataNotice = NO;
-  }
-  return self;
-}
 
 - (Class)cellClass {
   return [HistoryEntriesStatusCell class];
@@ -62,7 +52,7 @@
 - (void)configureCell:(HistoryEntriesStatusCell*)cell {
   [super configureCell:cell];
   [cell setDelegate:self];
-  if (self.hidden || !self.showsOtherBrowsingDataNotice) {
+  if (self.hidden) {
     cell.textLabel.text = nil;
   } else {
     cell.textLabel.text =
@@ -78,8 +68,7 @@
 }
 
 - (BOOL)isEqualToHistoryEntriesStatusItem:(HistoryEntriesStatusItem*)object {
-  return self.hidden == object.hidden &&
-         self.showsOtherBrowsingDataNotice == self.showsOtherBrowsingDataNotice;
+  return self.hidden == object.hidden;
 }
 
 - (BOOL)isEqual:(id)object {

ios/chrome/browser/ui/history/history_entries_status_item_unittest.mm

@@ -50,39 +50,16 @@ namespace {
 using HistoryEntriesStatusItemTest = PlatformTest;
 
 // Tests that configuring a cell for HistoryEntriesStatusItem with hidden
-// property set to YES results in an empty label, regardless of what
-// showsOtherBrowsingDataNotice is set to.
+// property set to YES results in an empty label.
 TEST_F(HistoryEntriesStatusItemTest, TestHidden) {
   HistoryEntriesStatusItem* item =
       [[HistoryEntriesStatusItem alloc] initWithType:0];
   item.hidden = YES;
-  item.showsOtherBrowsingDataNotice = YES;
   HistoryEntriesStatusCell* cell = [[HistoryEntriesStatusCell alloc] init];
   [item configureCell:cell];
   EXPECT_FALSE(cell.textLabel.text);
 }
 
-// Tests that configuring a cell for HistoryEntriesStatusItem with
-// showsOtherBrowsingDataNotice set to YES adds other browsing
-// data text to the label, while set to NO has no text.
-TEST_F(HistoryEntriesStatusItemTest, TestOtherBrowsingDataNotice) {
-  HistoryEntriesStatusItem* item =
-      [[HistoryEntriesStatusItem alloc] initWithType:0];
-  HistoryEntriesStatusCell* cell = [[HistoryEntriesStatusCell alloc] init];
-  item.hidden = NO;
-  item.showsOtherBrowsingDataNotice = YES;
-  [item configureCell:cell];
-  NSString* label_text =
-      l10n_util::GetNSString(IDS_IOS_HISTORY_OTHER_FORMS_OF_HISTORY);
-  NSRange range;
-  label_text = ParseStringWithLink(label_text, &range);
-  EXPECT_NSEQ(label_text, cell.textLabel.text);
-
-  item.showsOtherBrowsingDataNotice = NO;
-  [item configureCell:cell];
-  EXPECT_NSEQ(nil, cell.textLabel.text);
-}
-
 // Tests that tapping on links on a configured cell invokes
 // the HistoryEntriesStatusItemDelegate method.
 TEST_F(HistoryEntriesStatusItemTest, TestDelegate) {
@@ -93,7 +70,6 @@ TEST_F(HistoryEntriesStatusItemTest, TestDelegate) {
       [[MockEntriesStatusItemDelegate alloc] init];
   item.delegate = delegate;
   item.hidden = NO;
-  item.showsOtherBrowsingDataNotice = YES;
   [item configureCell:cell];
 
   // Layout the cell so that links are drawn.