[Mac] Do not draw pinned tab favicons on half pixels.

chrome/browser/ui/cocoa/tabs/tab_controller.mm

 // Copyright (c) 2011 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 "chrome/browser/ui/cocoa/tabs/tab_controller.h"
+
+#include <cmath>
+
 #include "base/mac/mac_util.h"
 #import "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/menu_controller.h"
-#import "chrome/browser/ui/cocoa/tabs/tab_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_controller_target.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #import "chrome/common/extensions/extension.h"
 #include "grit/generated_resources.h"
 #import "third_party/GTM/AppKit/GTMFadeTruncatingTextFieldCell.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
 @implementation TabController
 
@@ skipping 167 matching lines @@
   [iconView_ removeFromSuperview];
   iconView_ = iconView;
   if ([self app] || [self mini]) {
     NSRect appIconFrame = [iconView frame];
     appIconFrame.origin = originalIconFrame_.origin;
 
     const CGFloat tabWidth = [self app] ? [TabController appTabWidth]
                                         : [TabController miniTabWidth];
 
     // Center the icon.
-    appIconFrame.origin.x = (tabWidth - NSWidth(appIconFrame)) / 2.0;
+    appIconFrame.origin.x =
+        std::floor((tabWidth - NSWidth(appIconFrame)) / 2.0);
     [iconView_ setFrame:appIconFrame];
   } else {
     [iconView_ setFrame:originalIconFrame_];
   }
   // Ensure that the icon is suppressed if no icon is set or if the tab is too
   // narrow to display one.
   [self updateVisibility];
 
   if (iconView_)
     [[self view] addSubview:iconView_];
@@ skipping 119 matching lines @@
 // TabStripDragController.
 - (BOOL)tabCanBeDragged:(TabController*)controller {
   return [[target_ dragController] tabCanBeDragged:controller];
 }
 
 - (void)maybeStartDrag:(NSEvent*)event forTab:(TabController*)tab {
   [[target_ dragController] maybeStartDrag:event forTab:tab];
 }
 
 @end