[iOS] Add delete in SettingsTableView's toolbar

This CL adds a toolbar with a "delete" item in the
SettingsRootTableViewController, displayed when the item selection is
not nil.

Bug: 894791
Change-Id: Ifffc2b774ab96bad97814cdf80829f2f0b74d77a
Reviewed-on: https://chromium-review.googlesource.com/c/1331469
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607534}

ios/chrome/app/strings/ios_strings.grd

@@ -1391,6 +1391,9 @@ Handoff must also be enabled in the General section of Settings, and your device
       <message name="IDS_IOS_SETTING_ON" desc="Generic status label displayed in Settings to show that a setting is currently turned on. [Length: 5em] [iOS only]">
         On
       </message>
+      <message name="IDS_IOS_SETTINGS_TOOLBAR_DELETE" desc="Label of the button displayed on the bottom toolbar of the settings' collections when they are in edit mode. Pressing this button deletes the currently selected items.">
+        Delete
+      </message>
       <message name="IDS_IOS_TOGGLE_SETTING_SWITCH_ACCESSIBILITY_HINT" desc="Action hint for any switch in settings. This is spoken by VoiceOver. [iOS only]">
         Double tap to toggle setting
       </message>

ios/chrome/browser/ui/settings/settings_root_table_view_controller.h

@@ -50,6 +50,11 @@
 // editing mode of this controller.
 - (void)editButtonPressed;
 
+// Called when this ViewController toolbar's delete item has been tapped.
+// |indexPaths| is the index paths of the currently selected item to be deleted.
+// Default implementation removes the items.
+- (void)deleteItems:(NSArray<NSIndexPath*>*)indexPaths;
+
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_SETTINGS_SETTINGS_ROOT_TABLE_VIEW_CONTROLLER_H_

ios/chrome/browser/ui/settings/settings_root_table_view_controller.mm

@@ -19,8 +19,16 @@
 #error "This file requires ARC support."
 #endif
 
+@interface SettingsRootTableViewController ()
+
+// Delete button for the toolbar.
+@property(nonatomic, strong) UIBarButtonItem* deleteButton;
+
+@end
+
 @implementation SettingsRootTableViewController
 
+@synthesize deleteButton = _deleteButton;
 @synthesize dispatcher = _dispatcher;
 
 #pragma mark - Public
@@ -35,8 +43,30 @@
   }
 }
 
+#pragma mark - Property
+
+- (UIBarButtonItem*)deleteButton {
+  if (!_deleteButton) {
+    _deleteButton = [[UIBarButtonItem alloc]
+        initWithTitle:l10n_util::GetNSString(IDS_IOS_SETTINGS_TOOLBAR_DELETE)
+                style:UIBarButtonItemStylePlain
+               target:self
+               action:@selector(deleteButtonCallback)];
+    _deleteButton.tintColor = [UIColor redColor];
+  }
+  return _deleteButton;
+}
+
 #pragma mark - UIViewController
 
+- (NSArray<UIBarButtonItem*>*)toolbarItems {
+  UIBarButtonItem* flexibleSpace = [[UIBarButtonItem alloc]
+      initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
+                           target:nil
+                           action:nil];
+  return @[ flexibleSpace, self.deleteButton, flexibleSpace ];
+}
+
 - (void)viewDidLoad {
   self.styler.tableViewBackgroundColor =
       [UIColor groupTableViewBackgroundColor];
@@ -57,6 +87,31 @@
   }
 }
 
+- (void)viewWillDisappear:(BOOL)animated {
+  [super viewWillDisappear:animated];
+  [self.navigationController setToolbarHidden:YES animated:YES];
+}
+
+#pragma mark - UITableViewDelegate
+
+- (void)tableView:(UITableView*)tableView
+    didSelectRowAtIndexPath:(NSIndexPath*)indexPath {
+  if (!self.tableView.editing)
+    return;
+
+  if (self.navigationController.toolbarHidden)
+    [self.navigationController setToolbarHidden:NO animated:YES];
+}
+
+- (void)tableView:(UITableView*)tableView
+    didDeselectRowAtIndexPath:(NSIndexPath*)indexPath {
+  if (!self.tableView.editing)
+    return;
+
+  if (self.tableView.indexPathsForSelectedRows.count == 0)
+    [self.navigationController setToolbarHidden:YES animated:YES];
+}
+
 #pragma mark - TableViewLinkHeaderFooterItemDelegate
 
 - (void)view:(TableViewLinkHeaderFooterView*)view didTapLinkURL:(GURL)URL {
@@ -68,6 +123,10 @@
 
 #pragma mark - Private
 
+- (void)deleteButtonCallback {
+  [self deleteItems:self.tableView.indexPathsForSelectedRows];
+}
+
 - (UIBarButtonItem*)doneButtonIfNeeded {
   if (self.shouldHideDoneButton) {
     return nil;
@@ -115,4 +174,13 @@
   [self updateEditButton];
 }
 
+- (void)deleteItems:(NSArray<NSIndexPath*>*)indexPaths {
+  [self.tableView performBatchUpdates:^{
+    [self removeFromModelItemAtIndexPaths:indexPaths];
+    [self.tableView deleteRowsAtIndexPaths:indexPaths
+                          withRowAnimation:UITableViewRowAnimationAutomatic];
+  }
+                           completion:nil];
+}
+
 @end

ios/chrome/browser/ui/settings/settings_root_table_view_controller_unittest.mm

@@ -74,3 +74,50 @@ TEST_F(SettingsRootTableViewControllerTest, TestUpdateEditButton) {
   EXPECT_NSEQ(l10n_util::GetNSString(IDS_IOS_NAVIGATION_BAR_EDIT_BUTTON),
               controller.navigationItem.rightBarButtonItem.title);
 }
+
+// Tests that the delete button in the bottom toolbar is displayed only when the
+// collection is being edited.
+TEST_F(SettingsRootTableViewControllerTest, TestDeleteToolbar) {
+  SettingsRootTableViewController* controller = Controller();
+
+  id mockController = OCMPartialMock(controller);
+  id mockTableView = OCMPartialMock(controller.tableView);
+  SettingsNavigationController* navigationController = NavigationController();
+  OCMStub([mockController navigationController])
+      .andReturn(navigationController);
+
+  NSIndexPath* testIndexPath = [NSIndexPath indexPathForRow:0 inSection:0];
+  NSMutableArray* testSelectedItems = [NSMutableArray array];
+  [testSelectedItems addObject:testIndexPath];
+  ASSERT_TRUE(navigationController.toolbarHidden);
+
+  // Test that if the table view isn't being edited, the toolbar is still
+  // hidden.
+  controller.tableView.editing = NO;
+  [controller tableView:controller.tableView
+      didSelectRowAtIndexPath:testIndexPath];
+  EXPECT_TRUE(navigationController.toolbarHidden);
+
+  // Test that if the table view is being edited, the toolbar is displayed when
+  // the element is selected.
+  controller.tableView.editing = YES;
+  EXPECT_TRUE(navigationController.toolbarHidden);
+  [controller tableView:controller.tableView
+      didSelectRowAtIndexPath:testIndexPath];
+  EXPECT_FALSE(navigationController.toolbarHidden);
+
+  // Test that if the table view is being edited, the toolbar is not hidden when
+  // an element is deselected but some elements are still selected.
+  OCMStub([mockTableView indexPathsForSelectedRows])
+      .andReturn(testSelectedItems);
+  [controller tableView:controller.tableView
+      didDeselectRowAtIndexPath:testIndexPath];
+  EXPECT_FALSE(navigationController.toolbarHidden);
+
+  // Test that if the table view is being edited, the toolbar is hidden when the
+  // last selected element is deselected.
+  [testSelectedItems removeAllObjects];
+  [controller tableView:controller.tableView
+      didDeselectRowAtIndexPath:testIndexPath];
+  EXPECT_TRUE(navigationController.toolbarHidden);
+}