[iOS][Password Check] Fixed activity indicator for iOS 12

This change fixes bug for iOS 12 (and earlier) when activity indicator
is not visible by changing it's color from white to gray. The change
has no effect on iOS 13 and later.

Bug: 1116406
Change-Id: Ia8852bbfde208c7ff006da607b702ad97f12b8cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2356384
Commit-Queue: Viktor Semeniuk <vsemeniuk@google.com>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798483}

ios/chrome/browser/ui/settings/cells/settings_check_cell.mm

@@ -5,6 +5,7 @@
 #import "ios/chrome/browser/ui/settings/cells/settings_check_cell.h"
 
 #include "base/check.h"
+#include "base/ios/ios_util.h"
 #include "ios/chrome/browser/ui/table_view/cells/table_view_cells_constants.h"
 #import "ios/chrome/browser/ui/util/uikit_ui_util.h"
 #import "ios/chrome/common/ui/colors/UIColor+cr_semantic_colors.h"
@@ -101,7 +102,15 @@ const CGFloat kIconImageSize = 28;
     _trailingImageView.hidden = YES;
     [contentView addSubview:_trailingImageView];
     // |activityIndictor| attributes.
-    _activityIndicator = [[UIActivityIndicatorView alloc] init];
+    if (base::ios::IsRunningOnIOS13OrLater()) {
+      // Creates default activity indicator. Color depends on appearance.
+      _activityIndicator = [[UIActivityIndicatorView alloc] init];
+    } else {
+      // For iOS 12 and lower the color should be always gray otherwise
+      // indicator is not visible.
+      _activityIndicator = [[UIActivityIndicatorView alloc]
+          initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
+    }
     _activityIndicator.translatesAutoresizingMaskIntoConstraints = NO;
     _activityIndicator.hidden = YES;
     [contentView addSubview:_activityIndicator];