Upstream Chrome on iOS source code [4/11].

ios/chrome/browser/ui/elements/activity_overlay_view_controller.mm

+// Copyright 2016 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.
+
+#import "ios/chrome/browser/ui/elements/activity_overlay_view_controller.h"
+
+#import "ios/chrome/browser/ui/material_components/activity_indicator.h"
+#import "ios/chrome/browser/ui/uikit_ui_util.h"
+#import "ios/third_party/material_components_ios/src/components/ActivityIndicator/src/MaterialActivityIndicator.h"
+
+namespace {
+// Size of the activity indicator.
+const CGFloat kActivityIndicatorSize = 48;
+// Alpha of the presented view's background.
+const CGFloat kBackgroundAlpha = 0.5;
+}
+
+@implementation ActivityOverlayViewController
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+  self.view.backgroundColor = [UIColor colorWithWhite:0 alpha:kBackgroundAlpha];
+
+  MDCActivityIndicator* activityIndicator = [[[MDCActivityIndicator alloc]
+      initWithFrame:CGRectMake(0, 0, kActivityIndicatorSize,
+                               kActivityIndicatorSize)] autorelease];
+  activityIndicator.translatesAutoresizingMaskIntoConstraints = NO;
+  [self.view addSubview:activityIndicator];
+  AddSameCenterConstraints(self.view, activityIndicator);
+  activityIndicator.cycleColors = ActivityIndicatorBrandedCycleColors();
+  [activityIndicator startAnimating];
+}
+
+@end