[cocoa] increase tab strip contrast in "Increase Contrast" mode

chrome/browser/themes/theme_service_mac.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.
 
 #include "chrome/browser/themes/theme_service.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "chrome/browser/themes/browser_theme_pack.h"
 #include "chrome/browser/themes/theme_properties.h"
 #include "grit/theme_resources.h"
 #include "skia/ext/skia_utils_mac.h"
 #import "third_party/google_toolbox_for_mac/src/AppKit/GTMNSColor+Luminance.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/image/image.h"
 
+@interface NSWorkspace (Redeclarations)
+
+@property(readonly) BOOL accessibilityDisplayShouldIncreaseContrast;
+
+@end
+
 NSString* const kBrowserThemeDidChangeNotification =
     @"BrowserThemeDidChangeNotification";
 
 typedef ThemeProperties Properties;
 
 const int kMaterialDesignIdOffset = 1000000;
 
 namespace {
 
 void HSLToHSB(const color_utils::HSL& hsl, CGFloat* h, CGFloat* s, CGFloat* b) {
@@ skipping 368 matching lines @@
   return theme_service_.GetNSColor(id, incognito_);
 }
 
 NSColor* ThemeService::BrowserThemeProvider::GetNSColorTint(int id) const {
   return theme_service_.GetNSColorTint(id);
 }
 
 NSGradient* ThemeService::BrowserThemeProvider::GetNSGradient(int id) const {
   return theme_service_.GetNSGradient(id);
 }
+
+bool ThemeService::BrowserThemeProvider::ShouldIncreaseContrast() const {
+  NSWorkspace* workspace = [NSWorkspace sharedWorkspace];
+  if ([workspace
+          respondsToSelector:@selector(
+                                 accessibilityDisplayShouldIncreaseContrast)]) {
+    return workspace.accessibilityDisplayShouldIncreaseContrast == YES;
+  }
+  return false;
+}