Upstream Chrome on iOS source code [3/11].

ios/chrome/browser/ui/bookmarks/bookmark_elevated_toolbar.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.
+
+#import "ios/chrome/browser/ui/bookmarks/bookmark_elevated_toolbar.h"
+
+#include "base/mac/objc_property_releaser.h"
+#import "ios/third_party/material_components_ios/src/components/ShadowElevations/src/MaterialShadowElevations.h"
+#import "ios/third_party/material_components_ios/src/components/ShadowLayer/src/MaterialShadowLayer.h"
+
+@implementation BookmarksElevatedToolbar {
+  base::mac::ObjCPropertyReleaser _propertyReleaser_BookmarksElevatedToolbar;
+}
+
+@synthesize shadowLayer = _shadowLayer;
+
+#pragma mark - Lifecycle
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    _propertyReleaser_BookmarksElevatedToolbar.Init(
+        self, [BookmarksElevatedToolbar class]);
+  }
+  return self;
+}
+
+#pragma mark - Properties
+
+- (MDCShadowLayer*)shadowLayer {
+  if (!_shadowLayer) {
+    _shadowLayer = [[MDCShadowLayer alloc] init];
+    _shadowLayer.elevation = MDCShadowElevationNone;
+    [self.layer addSublayer:self.shadowLayer];
+  }
+  return _shadowLayer;
+}
+
+- (void)setShadowElevation:(CGFloat)shadowElevation {
+  self.shadowLayer.elevation = shadowElevation;
+}
+
+- (CGFloat)shadowElevation {
+  return self.shadowLayer.elevation;
+}
+
+#pragma mark - UIView
+
+- (void)layoutSubviews {
+  [super layoutSubviews];
+  self.shadowLayer.frame = self.layer.bounds;
+}
+
+@end