Have the toolbar's KAV respect the safeAreaLayoutGuide on iOS11.

Bug: 764692
Change-Id: I3e2493f770e8218aa9a5eb0351dfc0db0612832d
Reviewed-on: https://chromium-review.googlesource.com/664809
Commit-Queue: Jean-François Geyelin <jif@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501638}

ios/chrome/browser/ui/toolbar/keyboard_assist/toolbar_keyboard_accessory_view.mm

@@ -88,6 +88,19 @@
   [self addSubview:searchStackView];
 
   // Position the stack views.
+  if (@available(iOS 11, *)) {
+    UILayoutGuide* layoutGuide = self.safeAreaLayoutGuide;
+    [NSLayoutConstraint activateConstraints:@[
+      [searchStackView.leadingAnchor
+          constraintEqualToAnchor:layoutGuide.leadingAnchor
+                         constant:kHorizontalMargin],
+      [shortcutStackView.trailingAnchor
+          constraintEqualToAnchor:layoutGuide.trailingAnchor
+                         constant:-kHorizontalMargin],
+      [searchStackView.trailingAnchor
+          constraintLessThanOrEqualToAnchor:shortcutStackView.leadingAnchor]
+    ]];
+  } else {
     NSArray* constraints = @[
       @"H:|-horizontalMargin-[searchStackView]-(>=0)-[shortcutStackView]",
       @"[shortcutStackView]-horizontalMargin-|",
@@ -100,6 +113,7 @@
       @"horizontalMargin" : @(kHorizontalMargin),
     };
     ApplyVisualConstraintsWithMetrics(constraints, viewsDictionary, metrics);
+  }
   AddSameCenterYConstraint(searchStackView, self);
   AddSameCenterYConstraint(shortcutStackView, self);
 }
@@ -135,6 +149,17 @@
   return YES;
 }
 
+- (void)layoutMarginsDidChange {
+  NSLog(@"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
+  NSLog(@"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
+  NSLog(@"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
+  NSLog(@"$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$");
+
+  NSLog(@"%i", self.preservesSuperviewLayoutMargins);
+  NSLog(@"%f %f", self.layoutMargins.left, self.layoutMargins.right);
+  [super layoutMarginsDidChange];
+}
+
 - (void)keyboardButtonPressed:(id)sender {
   UIButton* button = base::mac::ObjCCastStrict<UIButton>(sender);
   [[UIDevice currentDevice] playInputClick];