[iOS] Moving up buttons in sign-in and first-run views inside the safe area

The sign-in/firstrun buttons is moved inside the safe area (related to
the iPhone X like).
The patch has been tested with rotation.

  ** Before **
 - First run:
https://drive.google.com/open?id=1Ig3SCaKTeCZkf3KfCnRHfPpAA9mZdLSB
 - Sign-in with first run:
https://drive.google.com/open?id=1arrBQ44c9kj7_R8xIykEfxLcJZjfTlZT
 - Sign-in portrait:
https://drive.google.com/open?id=17UlTFkc416iU72LeMFgg9PoEG-gRVXCc
 - Sign-in landscape:
https://drive.google.com/open?id=1pqC00vqx6AtHDJHXSxc_0yZ2Qr_1O66l

  ** After **
 - First run:
https://drive.google.com/open?id=1c6rJtftJInGlNgLTj19jmsbzgRf3hQZv
 - Sign-in with first run:
https://drive.google.com/open?id=19GRHlX6HdyO5HnPkVDzKCbxfcwSsyFyn
 - Sign-in portrait:
https://drive.google.com/open?id=187VDZsNLMzI50q4RLi2eAaLsXs7aZ6Zm
 - Sign-in landscape:
https://drive.google.com/open?id=1Q_WCYA8-JMI5cRtshLKAjFIXk9vLaNEn

Bug: 864225
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I33478974bbb0de2180ab842eb07321dcf5140ed0
Reviewed-on: https://chromium-review.googlesource.com/c/1286659Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601082}

ios/chrome/browser/ui/authentication/chrome_signin_view_controller.mm

@@ -69,11 +69,6 @@ namespace {
 // Default animation duration.
 const CGFloat kAnimationDuration = 0.5f;
 
-enum LayoutType {
-  LAYOUT_REGULAR,
-  LAYOUT_COMPACT,
-};
-
 // Minimum duration of the pending state in milliseconds.
 const int64_t kMinimunPendingStateDurationMs = 300;
 
@@ -381,6 +376,38 @@ enum AuthenticationState {
   _embeddedView = nil;
 }
 
+- (void)updateLayout {
+  AuthenticationViewConstants constants;
+  if ([self.traitCollection horizontalSizeClass] ==
+      UIUserInterfaceSizeClassRegular) {
+    constants = kRegularConstants;
+  } else {
+    constants = kCompactConstants;
+  }
+
+  [self layoutButtons:constants];
+
+  CGSize viewSize = self.view.bounds.size;
+  CGFloat collectionViewHeight =
+      _primaryButton.frame.origin.y - constants.ButtonTopPadding;
+  CGRect collectionViewFrame =
+      CGRectMake(0, 0, viewSize.width, collectionViewHeight);
+  [_embeddedView setFrame:collectionViewFrame];
+
+  // Layout the gradient view right above the buttons.
+  CGFloat gradientOriginY = _primaryButton.frame.origin.y -
+                            constants.ButtonTopPadding -
+                            constants.GradientHeight;
+  [_gradientView setFrame:CGRectMake(0, gradientOriginY, viewSize.width,
+                                     constants.GradientHeight)];
+  [_gradientLayer setFrame:[_gradientView bounds]];
+
+  // Layout the activity indicator in the center of the view.
+  CGRect bounds = self.view.bounds;
+  [_activityIndicator
+      setCenter:CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds))];
+}
+
 #pragma mark - Accessibility
 
 - (BOOL)accessibilityPerformEscape {
@@ -883,6 +910,11 @@ enum AuthenticationState {
   }
 }
 
+- (void)viewSafeAreaInsetsDidChange {
+  [super viewSafeAreaInsetsDidChange];
+  [self updateLayout];
+}
+
 #pragma mark - Events
 
 - (void)onPrimaryButtonPressed:(id)sender {
@@ -990,38 +1022,7 @@ enum AuthenticationState {
 
 - (void)viewDidLayoutSubviews {
   [super viewDidLayoutSubviews];
-
-  AuthenticationViewConstants constants;
-  if ([self.traitCollection horizontalSizeClass] ==
-      UIUserInterfaceSizeClassRegular) {
-    constants = kRegularConstants;
-  } else {
-    constants = kCompactConstants;
-  }
-
-  [self layoutButtons:constants];
-
-  CGSize viewSize = self.view.bounds.size;
-  CGFloat collectionViewHeight =
-      viewSize.height - _primaryButton.frame.size.height -
-      constants.ButtonBottomPadding - constants.ButtonTopPadding;
-  CGRect collectionViewFrame =
-      CGRectMake(0, 0, viewSize.width, collectionViewHeight);
-  [_embeddedView setFrame:collectionViewFrame];
-
-  // Layout the gradient view right above the buttons.
-  CGFloat gradientOriginY = CGRectGetHeight(self.view.bounds) -
-                            constants.ButtonBottomPadding -
-                            constants.ButtonTopPadding -
-                            constants.ButtonHeight - constants.GradientHeight;
-  [_gradientView setFrame:CGRectMake(0, gradientOriginY, viewSize.width,
-                                     constants.GradientHeight)];
-  [_gradientLayer setFrame:[_gradientView bounds]];
-
-  // Layout the activity indicator in the center of the view.
-  CGRect bounds = self.view.bounds;
-  [_activityIndicator
-      setCenter:CGPointMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds))];
+  [self updateLayout];
 }
 
 - (void)layoutButtons:(const AuthenticationViewConstants&)constants {
@@ -1040,6 +1041,9 @@ enum AuthenticationState {
   primaryButtonLayout.position.originY = CGRectGetHeight(self.view.bounds) -
                                          constants.ButtonBottomPadding -
                                          constants.ButtonHeight;
+  if (@available(iOS 11.0, *)) {
+    primaryButtonLayout.position.originY -= self.view.safeAreaInsets.bottom;
+  }
   primaryButtonLayout.size.height = constants.ButtonHeight;
   [_primaryButton setFrame:LayoutRectGetRect(primaryButtonLayout)];
 

ios/chrome/browser/ui/first_run/welcome_to_chrome_view.mm

@@ -320,6 +320,11 @@ const char kPrivacyNoticeUrl[] = "internal://privacy-notice";
   [self configureSubviews];
 }
 
+- (void)safeAreaInsetsDidChange {
+  [super safeAreaInsetsDidChange];
+  [self layoutOKButton];
+}
+
 - (void)layoutSubviews {
   [super layoutSubviews];
   [self layoutTitleLabel];
@@ -494,10 +499,15 @@ const char kPrivacyNoticeUrl[] = "internal://privacy-notice";
   CGFloat OKButtonBottomPadding =
       kOKButtonBottomPadding[self.cr_widthSizeClass];
   CGSize OKButtonSize = self.OKButton.bounds.size;
-  self.OKButton.frame = AlignRectOriginAndSizeToPixels(CGRectMake(
-      (CGRectGetWidth(self.bounds) - OKButtonSize.width) / 2.0,
-      CGRectGetMaxY(self.bounds) - OKButtonSize.height - OKButtonBottomPadding,
-      OKButtonSize.width, OKButtonSize.height));
+  CGFloat bottomSafeArea = 0;
+  if (@available(iOS 11.0, *)) {
+    bottomSafeArea = self.safeAreaInsets.bottom;
+  }
+  self.OKButton.frame = AlignRectOriginAndSizeToPixels(
+      CGRectMake((CGRectGetWidth(self.bounds) - OKButtonSize.width) / 2.0,
+                 CGRectGetMaxY(self.bounds) - OKButtonSize.height -
+                     OKButtonBottomPadding - bottomSafeArea,
+                 OKButtonSize.width, OKButtonSize.height));
 }
 
 - (void)traitCollectionDidChange: