Hide/show accessory view on inactive window.

FormInputAccessoryView is only fully dismissed when keyboard is hidden.
In multiwindow, it is possible that keyboard stays on screen when a text
field edition ends, if the keyboard is used in another window.

Hide the accessory view to avoid having an inactive accessory view on
screen.

Bug: 1125110
Change-Id: I1ff717af263589185e69eaddff8e469edde8c77b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2401102Reviewed-by: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806110}

ios/chrome/browser/ui/settings/autofill/autofill_edit_table_view_controller.mm

@@ -83,6 +83,7 @@
 - (void)textFieldDidBeginEditing:(UITextField*)textField {
   TableViewTextEditCell* cell = [self autofillEditCellForTextField:textField];
   _currentEditingCell = cell;
+  self.formInputAccessoryView.hidden = NO;
   [textField setInputAccessoryView:self.formInputAccessoryView];
   [self updateAccessoryViewButtonState];
 }
@@ -91,6 +92,7 @@
   TableViewTextEditCell* cell = [self autofillEditCellForTextField:textField];
   DCHECK(_currentEditingCell == cell);
   [textField setInputAccessoryView:nil];
+  self.formInputAccessoryView.hidden = YES;
   _currentEditingCell = nil;
 }