[ios clean] Toolbar displays total number of tabs.

ios/clean/chrome/browser/ui/toolbar/toolbar_button.mm

 // Copyright 2017 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/clean/chrome/browser/ui/toolbar/toolbar_button.h"
 
+#import "ios/chrome/browser/ui/uikit_ui_util.h"
+
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 @implementation ToolbarButton
 @synthesize visibilityMask = _visibilityMask;
 @synthesize hiddenInCurrentSizeClass = _hiddenInCurrentSizeClass;
 @synthesize hiddenInCurrentState = _hiddenInCurrentState;
 
 + (instancetype)toolbarButtonWithImageForNormalState:(UIImage*)normalImage
                             imageForHighlightedState:(UIImage*)highlightedImage
                                imageForDisabledState:(UIImage*)disabledImage {
   ToolbarButton* button = [[self class] buttonWithType:UIButtonTypeCustom];
   [button setImage:normalImage forState:UIControlStateNormal];
   [button setImage:highlightedImage forState:UIControlStateHighlighted];
   [button setImage:disabledImage forState:UIControlStateDisabled];
+  button.titleLabel.textAlignment = NSTextAlignmentCenter;
   button.translatesAutoresizingMaskIntoConstraints = NO;
   return button;
 }
 
+- (void)layoutSubviews {
+  [super layoutSubviews];
+  // If the UIButton title has text it will center it on top of the image,
+  // this is currently used for the TabStripButton which displays the
+  // total number of tabs.
+  if (self.titleLabel.text) {
+    CGSize size = self.bounds.size;
+    CGPoint center = CGPointMake(size.width / 2, size.height / 2);
+    self.imageView.center = center;
+    self.imageView.frame = AlignRectToPixel(self.imageView.frame);
+    self.titleLabel.frame = self.bounds;
+  }
+}
+
 #pragma mark - Public Methods
 
 - (void)updateHiddenInCurrentSizeClass {
   BOOL newHiddenValue = YES;
   switch (self.traitCollection.horizontalSizeClass) {
     case UIUserInterfaceSizeClassRegular:
       newHiddenValue =
           !(self.visibilityMask & ToolbarComponentVisibilityRegularWidth);
       break;
     case UIUserInterfaceSizeClassCompact:
@@ skipping 14 matching lines @@
     self.hiddenInCurrentSizeClass = newHiddenValue;
     [self setHiddenForCurrentStateAndSizeClass];
   }
 }
 
 - (void)setHiddenForCurrentStateAndSizeClass {
   self.hidden = self.hiddenInCurrentState || self.hiddenInCurrentSizeClass;
 }
 
 @end