[iOS] Update tab counts in grid via delegate

Bug: 804552
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I183368403e1977c28dd0696532feff849fcbf0df
Reviewed-on: https://chromium-review.googlesource.com/966625
Commit-Queue: edchin <edchin@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543751}

ios/chrome/browser/ui/tab_grid/grid_view_controller.h

@@ -16,20 +16,18 @@
 
 // Protocol used to relay relevant user interactions from a grid UI.
 @protocol GridViewControllerDelegate
-// Tells the receiver that the item at |index| was selected in
+// Tells the delegate that the item at |index| was selected in
 // |gridViewController|.
 - (void)gridViewController:(GridViewController*)gridViewController
       didSelectItemAtIndex:(NSUInteger)index;
-// Tells the receiver that the item at |index| was closed in
+// Tells the delegate that the item at |index| was closed in
 // |gridViewController|.
 - (void)gridViewController:(GridViewController*)gridViewController
        didCloseItemAtIndex:(NSUInteger)index;
-// Tells the receiver that the last item was closed in |gridViewController|.
-- (void)lastItemWasClosedInGridViewController:
-    (GridViewController*)gridViewController;
-// Tells the receiver that the first item was added in |gridViewController|.
-- (void)firstItemWasAddedInGridViewController:
-    (GridViewController*)gridViewController;
+// Tells the delegate that the the number of items in |gridViewController|
+// changed to |count|.
+- (void)gridViewController:(GridViewController*)gridViewController
+        didChangeItemCount:(NSUInteger)count;
 @end
 
 // A view controller that contains a grid of items.
@@ -40,8 +38,6 @@
 @property(nonatomic, strong) UIView* emptyStateView;
 // Returns YES if the grid has no items.
 @property(nonatomic, readonly, getter=isGridEmpty) BOOL gridEmpty;
-// The number of items in the grid. Not all of the items may be visible.
-@property(nonatomic, readonly) NSUInteger itemCount;
 // The visual look of the grid.
 @property(nonatomic, assign) GridTheme theme;
 // Delegate is informed of user interactions in the grid UI.

ios/chrome/browser/ui/tab_grid/grid_view_controller.mm

@@ -82,6 +82,8 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
   [self.collectionView selectItemAtIndexPath:CreateIndexPath(self.selectedIndex)
                                     animated:animated
                               scrollPosition:UICollectionViewScrollPositionTop];
+  // Update the delegate, in case it wasn't set when |items| was populated.
+  [self.delegate gridViewController:self didChangeItemCount:self.items.count];
 }
 
 #pragma mark - Public
@@ -105,10 +107,6 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
   return self.items.count == 0;
 }
 
-- (NSUInteger)itemCount {
-  return self.items.count;
-}
-
 - (BOOL)isSelectedCellVisible {
   if (self.collectionView.indexPathsForSelectedItems.count == 0)
     return NO;
@@ -205,6 +203,7 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
   [self.collectionView selectItemAtIndexPath:CreateIndexPath(selectedIndex)
                                     animated:YES
                               scrollPosition:UICollectionViewScrollPositionTop];
+  [self.delegate gridViewController:self didChangeItemCount:self.items.count];
 }
 
 - (void)insertItem:(GridItem*)item
@@ -216,6 +215,7 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
   };
   if (![self isViewVisible]) {
     performDataSourceUpdates();
+    [self.delegate gridViewController:self didChangeItemCount:self.items.count];
     return;
   }
   auto performAllUpdates = ^{
@@ -228,9 +228,7 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
         selectItemAtIndexPath:CreateIndexPath(selectedIndex)
                      animated:YES
                scrollPosition:UICollectionViewScrollPositionNone];
-    if (self.items.count == 1) {
-      [self.delegate firstItemWasAddedInGridViewController:self];
-    }
+    [self.delegate gridViewController:self didChangeItemCount:self.items.count];
   };
   [self.collectionView performBatchUpdates:performAllUpdates
                                 completion:completion];
@@ -244,6 +242,7 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
   };
   if (![self isViewVisible]) {
     performDataSourceUpdates();
+    [self.delegate gridViewController:self didChangeItemCount:self.items.count];
     return;
   }
   auto performAllUpdates = ^{
@@ -258,8 +257,8 @@ NSIndexPath* CreateIndexPath(NSInteger index) {
                  scrollPosition:UICollectionViewScrollPositionNone];
     } else {
       self.collectionView.backgroundView.hidden = NO;
-      [self.delegate lastItemWasClosedInGridViewController:self];
     }
+    [self.delegate gridViewController:self didChangeItemCount:self.items.count];
   };
   [self.collectionView performBatchUpdates:performAllUpdates
                                 completion:completion];

ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.mm

@@ -439,7 +439,6 @@ typedef NS_ENUM(NSUInteger, TabGridConfiguration) {
   [self.topToolbar.pageControl addTarget:self
                                   action:@selector(pageControlChanged:)
                         forControlEvents:UIControlEventValueChanged];
-  [self updatePageControlItemCounts];
   NSArray* constraints = @[
     [topToolbar.topAnchor constraintEqualToAnchor:self.view.topAnchor],
     [topToolbar.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor],
@@ -632,13 +631,6 @@ typedef NS_ENUM(NSUInteger, TabGridConfiguration) {
   }
 }
 
-- (void)updatePageControlItemCounts {
-  self.topToolbar.pageControl.incognitoTabCount =
-      self.incognitoTabsViewController.itemCount;
-  self.topToolbar.pageControl.regularTabCount =
-      self.regularTabsViewController.itemCount;
-}
-
 // Translates the toolbar views offscreen and then animates them back in using
 // the transition coordinator. Transitions are preferred here since they don't
 // interact with the layout system at all.
@@ -697,18 +689,16 @@ typedef NS_ENUM(NSUInteger, TabGridConfiguration) {
   } else if (gridViewController == self.incognitoTabsViewController) {
     [self.incognitoTabsDelegate closeItemAtIndex:index];
   }
-  [self updatePageControlItemCounts];
-}
-
-- (void)lastItemWasClosedInGridViewController:
-    (GridViewController*)gridViewController {
-  [self configureButtonsForCurrentPage];
 }
 
-- (void)firstItemWasAddedInGridViewController:
-    (GridViewController*)gridViewController {
+- (void)gridViewController:(GridViewController*)gridViewController
+        didChangeItemCount:(NSUInteger)count {
   [self configureButtonsForCurrentPage];
-  [self updatePageControlItemCounts];
+  if (gridViewController == self.regularTabsViewController) {
+    self.topToolbar.pageControl.regularTabCount = count;
+  } else if (gridViewController == self.incognitoTabsViewController) {
+    self.topToolbar.pageControl.incognitoTabCount = count;
+  }
 }
 
 #pragma mark - Control actions
@@ -745,7 +735,6 @@ typedef NS_ENUM(NSUInteger, TabGridConfiguration) {
       // No-op. It is invalid to call insert new tab on remote tabs.
       break;
   }
-  [self updatePageControlItemCounts];
 }
 
 - (void)pageControlChanged:(id)sender {