Adding error handling to the connection flow.

remoting/ios/app/session_error_view.mm

+// Copyright 2017 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.
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+#import "remoting/ios/app/session_error_view.h"
+
+#import "ios/third_party/material_components_ios/src/components/Buttons/src/MaterialButtons.h"
+#import "remoting/ios/app/remoting_theme.h"
+
+// static const CGFloat kMargin = 5.f;

[Yuwei, 2017/07/05 21:43:42]

What are these commented numbers for?

[nicholss, 2017/07/06 20:49:02]

gone.

+// static const CGFloat kPadding = 8.f;
+// static const CGFloat kLineSpace = 12.f;
+static const CGFloat kReconnectButtonWidth = 120.f;
+static const CGFloat kReconnectButtonHeight = 30.f;
+
+@interface SessionErrorView () {
+  MDCRaisedButton* _reconnectButton;
+}
+@end
+
+@implementation SessionErrorView
+
+@synthesize delegate = _delegate;
+
+- (id)initWithFrame:(CGRect)frame {
+  self = [super initWithFrame:frame];
+  if (self) {
+    self.backgroundColor = [UIColor clearColor];
+
+    _reconnectButton = [[MDCRaisedButton alloc] init];
+    [_reconnectButton setElevation:4.0f forState:UIControlStateNormal];
+    [_reconnectButton setTitle:@"Reconnect" forState:UIControlStateNormal];
+    [_reconnectButton addTarget:self
+                         action:@selector(didTapReconnect:)
+               forControlEvents:UIControlEventTouchUpInside];
+    [self addSubview:_reconnectButton];
+  }
+  return self;
+}
+
+#pragma mark - UIView
+
+- (void)layoutSubviews {
+  [super layoutSubviews];
+  _reconnectButton.frame =
+      CGRectMake((self.frame.size.width - kReconnectButtonWidth) / 2.f, 0,

[Yuwei, 2017/07/05 21:43:42]

Will it be simpler to do self.center.x - kReconnectButtonWidth / 2.f? You can
also use the centerXAnchor if you like

[nicholss, 2017/07/06 20:49:02]

Used autolayout

+                 kReconnectButtonWidth, kReconnectButtonHeight);
+}
+
+#pragma mark - Private
+
+- (void)didTapReconnect:(id)sender {
+  if ([_delegate respondsToSelector:@selector(didTapReconnect)]) {
+    [_delegate didTapReconnect];
+  }
+}
+
+@end