Making the gradient click-through in ChromeSigninViewController

ios/chrome/browser/ui/authentication/chrome_signin_view_controller.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/authentication/chrome_signin_view_controller.h"
 
 #include <stdint.h>
 #include <cmath>
 #include <memory>
 
@@ skipping 674 matching lines @@
   _activityIndicator.reset(
       [[MDCActivityIndicator alloc] initWithFrame:CGRectZero]);
   [_activityIndicator setDelegate:self];
   [_activityIndicator setStrokeWidth:3];
   [_activityIndicator
       setCycleColors:@[ [[MDCPalette cr_bluePalette] tint500] ]];
   [self.view addSubview:_activityIndicator];
 
   _gradientView.reset([[UIView alloc] initWithFrame:CGRectZero]);
   _gradientLayer.reset([[CAGradientLayer layer] retain]);
+  [_gradientView setUserInteractionEnabled:NO];
   _gradientLayer.get().colors = [NSArray
       arrayWithObjects:(id)[[UIColor colorWithWhite:1 alpha:0] CGColor],
                        (id)[self.backgroundColor CGColor], nil];
   [[_gradientView layer] insertSublayer:_gradientLayer atIndex:0];
   [self.view addSubview:_gradientView];
 }
 
 - (void)viewWillAppear:(BOOL)animated {
   [super viewWillAppear:animated];
 
@@ skipping 237 matching lines @@
   }
   _hasConfirmationScreenReachedBottom = YES;
   [self setPrimaryButtonStyling:_primaryButton];
   [_primaryButton setTitle:[self acceptSigninButtonTitle]
                   forState:UIControlStateNormal];
   [_primaryButton setImage:nil forState:UIControlStateNormal];
   [self.view setNeedsLayout];
 }
 
 @end