[mac] Fixed window buttons positioning on Sierra.

chrome/browser/ui/cocoa/framed_browser_window.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/framed_browser_window.h"
 
 #include <math.h>
 #include <objc/runtime.h>
 #include <stddef.h>
 
@@ skipping 22 matching lines @@
 // - close/min in the background don't bring the window forward
 // - rollover effects work correctly
 
 // The NSLayoutConstraint class hierarchy only exists in the 10.11 SDK. When
 // targeting something lower, constraintEqualToAnchor:constant: needs to be
 // invoked using duck typing.
 #if !defined(MAC_OS_X_VERSION_10_11) || \
     MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_11
 @interface NSObject (NSLayoutConstraint)
 - (NSLayoutConstraint*)constraintEqualToAnchor:(id)anchor constant:(CGFloat)c;
+- (NSLayoutConstraint*)constraintEqualToAnchor:(id)anchor;
 @end
 #endif
 
 namespace {
 
 // Size of the gradient. Empirically determined so that the gradient looks
 // like what the heuristic does when there are just a few tabs.
 const CGFloat kWindowGradientHeight = 24.0;
 
 }
@@ skipping 225 matching lines @@
 
 #if !defined(MAC_OS_X_VERSION_10_11) || \
     MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_11
   id leadingSourceAnchorDuck = leadingSourceAnchor;
 #else
   NSLayoutXAxisAnchor* leadingSourceAnchorDuck = leadingSourceAnchor;
 #endif
   [[leadingSourceAnchorDuck constraintEqualToAnchor:leadingTargetAnchor
                                            constant:leadingOffset]
       setActive:YES];
+
+  [[[button bottomAnchor]
+      constraintEqualToAnchor:[[button superview] bottomAnchor]]
+          setActive:YES];
 }
 
 - (void)adjustCloseButton:(NSNotification*)notification {
   [self adjustButton:[notification object]
               ofKind:NSWindowCloseButton];
 }
 
 - (void)adjustMiniaturizeButton:(NSNotification*)notification {
   [self adjustButton:[notification object]
               ofKind:NSWindowMiniaturizeButton];
@@ skipping 218 matching lines @@
   [self childWindowsDidChange];
 }
 
 - (void)childWindowsDidChange {
   id delegate = [self delegate];
   if ([delegate respondsToSelector:@selector(childWindowsDidChange)])
     [delegate childWindowsDidChange];
 }
 
 @end