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

chrome/browser/themes/theme_service.h

 // Copyright (c) 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.
 
 #ifndef CHROME_BROWSER_THEMES_THEME_SERVICE_H_
 #define CHROME_BROWSER_THEMES_THEME_SERVICE_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 186 matching lines @@
         const override;
 #if defined(OS_MACOSX)
     bool UsingSystemTheme() const override;
     bool InIncognitoMode() const override;
     bool HasCustomColor(int id) const override;
     NSImage* GetNSImageNamed(int id) const override;
     NSColor* GetNSImageColorNamed(int id) const override;
     NSColor* GetNSColor(int id) const override;
     NSColor* GetNSColorTint(int id) const override;
     NSGradient* GetNSGradient(int id) const override;
+    bool ShouldIncreaseContrast() const override;
 #endif
 
    private:
     const ThemeService& theme_service_;
     bool incognito_;
 
     DISALLOW_COPY_AND_ASSIGN(BrowserThemeProvider);
   };
   friend class BrowserThemeProvider;
   friend class theme_service_internal::ThemeServiceTest;
@@ skipping 107 matching lines @@
 
   BrowserThemeProvider original_theme_provider_;
   BrowserThemeProvider incognito_theme_provider_;
 
   base::WeakPtrFactory<ThemeService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ThemeService);
 };
 
 #endif  // CHROME_BROWSER_THEMES_THEME_SERVICE_H_