Upstream Chrome on iOS source code [7/11].

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

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/browser/ui/settings/bar_button_activity_indicator.h"
+
+#include "base/mac/scoped_nsobject.h"
+#include "ios/chrome/browser/ui/ui_util.h"
+
+@implementation BarButtonActivityIndicator {
+  base::scoped_nsobject<UIActivityIndicatorView> activityIndicator_;
+}
+
+- (id)initWithFrame:(CGRect)frame {
+  self = [super initWithFrame:frame];
+  if (self) {
+    activityIndicator_.reset([[UIActivityIndicatorView alloc]
+        initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]);
+    [activityIndicator_ setBackgroundColor:[UIColor clearColor]];
+    [activityIndicator_ setHidesWhenStopped:YES];
+    [activityIndicator_ startAnimating];
+    [self addSubview:activityIndicator_];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [activityIndicator_ stopAnimating];
+  [super dealloc];
+}
+
+- (void)layoutSubviews {
+  [super layoutSubviews];
+  CGSize boundsSize = self.bounds.size;
+  CGPoint center = CGPointMake(boundsSize.width / 2, boundsSize.height / 2);
+  [activityIndicator_ setCenter:AlignPointToPixel(center)];
+}
+
+@end