Fix spacing on welcome screen for small screen (iPhone 4)

ios/chrome/browser/ui/first_run/welcome_to_chrome_view.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.
 
 #import "ios/chrome/browser/ui/first_run/welcome_to_chrome_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/chrome/browser/ui/UIView+SizeClassSupport.h"
@@ skipping 27 matching lines @@
 // The width of the container view for a REGULAR width size class.
 const CGFloat kContainerViewRegularWidth = 510.0;
 
 // The percentage of the view's width taken up by the container view for a
 // COMPACT width size class.
 const CGFloat kContainerViewCompactWidthPercentage = 0.8;
 
 // Layout constants.
 const CGFloat kImageTopPadding[SIZE_CLASS_COUNT] = {32.0, 50.0};
 const CGFloat kTOSLabelTopPadding[SIZE_CLASS_COUNT] = {34.0, 40.0};
-const CGFloat kOptInLabelTopPadding[SIZE_CLASS_COUNT] = {10.0, 14.0};
+const CGFloat kOptInLabelPadding[SIZE_CLASS_COUNT] = {10.0, 14.0};
 const CGFloat kCheckBoxPadding[SIZE_CLASS_COUNT] = {10.0, 16.0};
 const CGFloat kOKButtonBottomPadding[SIZE_CLASS_COUNT] = {32.0, 32.0};
 const CGFloat kOKButtonHeight[SIZE_CLASS_COUNT] = {36.0, 54.0};
 // Multiplier matches that used in LaunchScreen.xib to determine size of logo.
 const CGFloat kAppLogoProportionMultiplier = 0.381966;
 
 // Font sizes.
 const CGFloat kTitleLabelFontSize[SIZE_CLASS_COUNT] = {24.0, 36.0};
 const CGFloat kTOSLabelFontSize[SIZE_CLASS_COUNT] = {14.0, 21.0};
 const CGFloat kTOSLabelLineHeight[SIZE_CLASS_COUNT] = {20.0, 32.0};
@@ skipping 260 matching lines @@
   [self configureSubviews];
 }
 
 - (void)layoutSubviews {
   [super layoutSubviews];
   [self layoutTitleLabel];
   [self layoutImageView];
   [self layoutTOSLabel];
   [self layoutOptInLabel];
   [self layoutCheckBoxButton];
+  // The OK Button must be laid out before the container view so that the
+  // container view can take its position into account.
+  [self layoutOKButton];
   [self layoutContainerView];
-  [self layoutOKButton];
 }
 
 - (void)layoutTitleLabel {
   // The label is centered and top-aligned with the container view.
   CGSize containerSize = self.containerView.bounds.size;
   containerSize.height = CGFLOAT_MAX;
   CGSize titleLabelSize = [self.titleLabel sizeThatFits:containerSize];
   self.titleLabel.frame = AlignRectOriginAndSizeToPixels(
       CGRectMake((containerSize.width - titleLabelSize.width) / 2.0, 0.0,
                  titleLabelSize.width, titleLabelSize.height));
@@ skipping 50 matching lines @@
   CGSize TOSLabelSize = [self.TOSLabel sizeThatFits:containerSize];
   CGFloat TOSLabelTopPadding = kTOSLabelTopPadding[self.cr_heightSizeClass];
   self.TOSLabel.frame = AlignRectOriginAndSizeToPixels(
       CGRectMake((containerSize.width - TOSLabelSize.width) / 2.0,
                  CGRectGetMaxY(self.imageView.frame) + TOSLabelTopPadding,
                  TOSLabelSize.width, TOSLabelSize.height));
 }
 
 - (void)layoutOptInLabel {
   // The opt in label is laid out to the right (or left in RTL) of the check box
-  // button and below |TOSLabel| as specified by kOptInLabelTopPadding.
+  // button and below |TOSLabel| as specified by kOptInLabelPadding.
   CGSize checkBoxSize =
       [self.checkBoxButton imageForState:self.checkBoxButton.state].size;
   CGFloat checkBoxPadding = kCheckBoxPadding[self.cr_widthSizeClass];
   CGFloat optInLabelSidePadding = checkBoxSize.width + 2.0 * checkBoxPadding;
   CGSize optInLabelSize = [self.optInLabel
       sizeThatFits:CGSizeMake(CGRectGetWidth(self.containerView.bounds) -
                                   optInLabelSidePadding,
                               CGFLOAT_MAX)];
-  CGFloat optInLabelTopPadding = kOptInLabelTopPadding[self.cr_heightSizeClass];
+  CGFloat optInLabelTopPadding = kOptInLabelPadding[self.cr_heightSizeClass];
   CGFloat optInLabelOriginX =
       base::i18n::IsRTL() ? 0.0f : optInLabelSidePadding;
   self.optInLabel.frame = AlignRectOriginAndSizeToPixels(
       CGRectMake(optInLabelOriginX,
                  CGRectGetMaxY(self.TOSLabel.frame) + optInLabelTopPadding,
                  optInLabelSize.width, optInLabelSize.height));
   ios_internal::FixOrphanWord(self.optInLabel);
 }
 
 - (void)layoutCheckBoxButton {
@@ skipping 19 matching lines @@
   self.checkBoxButton.imageEdgeInsets = UIEdgeInsetsMake(
       (checkBoxButtonSize.height - checkBoxSize.height) / 2.0,
       base::i18n::IsRTL() ? largeHorizontalInset : smallHorizontalInset,
       (checkBoxButtonSize.height - checkBoxSize.height) / 2.0,
       base::i18n::IsRTL() ? smallHorizontalInset : largeHorizontalInset);
 }
 
 - (void)layoutContainerView {
   // The container view is resized according to the final layout of
   // |checkBoxButton|, which is its lowest subview.  The resized view is then
-  // centered horizontally and vertically.
+  // centered horizontally and vertically. If necessary, it is shifted up to
+  // allow |kOptInLabelPadding| between |optInLabel| and |OKButton|.
   CGSize containerViewSize = self.containerView.bounds.size;
   containerViewSize.height = CGRectGetMaxY(self.checkBoxButton.frame);
+
+  CGFloat padding = kOptInLabelPadding[self.cr_heightSizeClass];
+  CGFloat originY = fmin(
+      (CGRectGetHeight(self.bounds) - containerViewSize.height) / 2.0,
+      CGRectGetMinY(self.OKButton.frame) - padding - containerViewSize.height);
+
   self.containerView.frame = AlignRectOriginAndSizeToPixels(CGRectMake(
-      (CGRectGetWidth(self.bounds) - containerViewSize.width) / 2.0,
-      (CGRectGetHeight(self.bounds) - containerViewSize.height) / 2.0,
+      (CGRectGetWidth(self.bounds) - containerViewSize.width) / 2.0, originY,
       containerViewSize.width, CGRectGetMaxY(self.checkBoxButton.frame)));
 }
 
 - (void)layoutOKButton {
   // The OK button is laid out at the bottom of the view as specified by
   // kOKButtonBottomPadding.
   CGFloat OKButtonBottomPadding =
       kOKButtonBottomPadding[self.cr_widthSizeClass];
   CGSize OKButtonSize = self.OKButton.bounds.size;
   self.OKButton.frame = AlignRectOriginAndSizeToPixels(CGRectMake(
@@ skipping 78 matching lines @@
 
 - (void)OKButtonWasTapped {
   [self.delegate welcomeToChromeViewDidTapOKButton:self];
 }
 
 - (void)TOSLinkWasTapped {
   [self.delegate welcomeToChromeViewDidTapTOSLink:self];
 }
 
 @end