[ios clean] Add placeholder for NTP bookmarks, chrome home and open tabs.

ios/chrome/browser/ui/ntp/new_tab_page_view.mm

 // Copyright 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 "ios/chrome/browser/ui/ntp/new_tab_page_view.h"
 
 #include "base/logging.h"
 #include "base/mac/objc_property_releaser.h"
 #import "ios/chrome/browser/ui/ntp/new_tab_page_bar.h"
 #import "ios/chrome/browser/ui/ntp/new_tab_page_bar_item.h"
@@ skipping 62 matching lines @@
         selectedItemXOffset = CGRectGetMinX(item.view.frame);
       index++;
     }
 
     // Ensure the selected NTP panel is lined up correctly when the frame
     // changes.
     CGPoint point = CGPointMake(selectedItemXOffset, 0);
     [self.scrollView setContentOffset:point animated:NO];
   }
 
-  // Trigger a layout.  The |-layoutIfNeeded| call is required because sometimes
-  // |-layoutSubviews| is not successfully triggered when |-setNeedsLayout| is
-  // called after frame changes due to autoresizing masks.
-  [self setNeedsLayout];
-  [self layoutIfNeeded];
+  if (self.translatesAutoresizingMaskIntoConstraints) {

[marq (ping after 24h), 2017/04/05 12:22:47]

It's not clear to my why this is conditional here. Can you update the comment?

[justincohen, 2017/04/05 19:28:23]

Added a comment explaining why.

+    // Trigger a layout.  The |-layoutIfNeeded| call is required because
+    // sometimes
+    // |-layoutSubviews| is not successfully triggered when |-setNeedsLayout| is
+    // called after frame changes due to autoresizing masks.
+    [self setNeedsLayout];
+    [self layoutIfNeeded];
+  }
 }
 
 - (void)layoutSubviews {
   [super layoutSubviews];
 
   self.tabBar.hidden = !self.tabBar.items.count;
   if (self.tabBar.hidden) {
     self.scrollView.frame = self.bounds;
   } else {
     CGSize barSize = [self.tabBar sizeThatFits:self.bounds.size];
     self.tabBar.frame = CGRectMake(CGRectGetMinX(self.bounds),
                                    CGRectGetMaxY(self.bounds) - barSize.height,
                                    barSize.width, barSize.height);
     self.scrollView.frame = CGRectMake(
         CGRectGetMinX(self.bounds), CGRectGetMinY(self.bounds),
         CGRectGetWidth(self.bounds), CGRectGetMinY(self.tabBar.frame));
   }
+
+  if (!self.translatesAutoresizingMaskIntoConstraints) {
+    [self setFrame:self.frame];

[marq (ping after 24h), 2017/04/05 12:22:47]

This feels deeply wrong. Why is it needed?

[justincohen, 2017/04/05 19:28:23]

Added a comment explaining why.

+  }
 }
 
 - (void)updateScrollViewContentSize {
   CGSize contentSize = self.scrollView.bounds.size;
   // On iPhone, NTP doesn't scroll horizontally, as alternate panels are shown
   // modally. On iPad, panels are laid out side by side in the scroll view.
   if (IsIPadIdiom()) {
     contentSize.width *= self.tabBar.items.count;
   }
   self.scrollView.contentSize = contentSize;
 }
 
 - (CGRect)panelFrameForItemAtIndex:(NSUInteger)index {
   CGRect contentBounds = CGRectMake(0, 0, self.scrollView.contentSize.width,
                                     self.scrollView.contentSize.height);
   LayoutRect layout =
       LayoutRectForRectInBoundingRect(self.scrollView.bounds, contentBounds);
   layout.position.leading = layout.size.width * index;
   return LayoutRectGetRect(layout);
 }
 
 @end