Dynamically compute tab/frame separator color.

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 <set>
 #include <string>
@@ skipping 197 matching lines @@
 
    private:
     const ThemeService& theme_service_;
     bool incognito_;
 
     DISALLOW_COPY_AND_ASSIGN(BrowserThemeProvider);
   };
   friend class BrowserThemeProvider;
   friend class theme_service_internal::ThemeServiceTest;
 
+  // Key for cache of separator colors; pair is <tab color, frame color>.
+  using SeparatorColorKey = std::pair<SkColor, SkColor>;
+  using SeparatorColorCache = std::map<SeparatorColorKey, SkColor>;
+
+  // Computes the "toolbar top separator" color.  This color is drawn atop the
+  // frame to separate it from tabs, the toolbar, and the new tab button, as
+  // well as atop background tabs to separate them from other tabs or the
+  // toolbar.  We use semitransparent black or white so as to darken or lighten
+  // the frame, with the goal of contrasting with both the frame color and the
+  // active tab (i.e. toolbar) color.  (It's too difficult to try to find colors
+  // that will contrast with both of these as well as the background tab color,
+  // and contrasting with the foreground tab is the most important).
+  static SkColor GetSeparatorColor(SkColor tab_color, SkColor frame_color);
+
   // These methods provide the implementation for ui::ThemeProvider (exposed
   // via BrowserThemeProvider).
   gfx::ImageSkia* GetImageSkiaNamed(int id, bool incognito) const;
   SkColor GetColor(int id, bool incognito) const;
   int GetDisplayProperty(int id) const;
   base::RefCountedMemory* GetRawData(int id,
                                      ui::ScaleFactor scale_factor) const;
 #if defined(OS_MACOSX)
   NSImage* GetNSImageNamed(int id, bool incognito) const;
   NSColor* GetNSImageColorNamed(int id, bool incognito) const;
@@ skipping 60 matching lines @@
   // The id of the theme extension which has just been installed but has not
   // been loaded yet. The theme extension with |installed_pending_load_id_| may
   // never be loaded if the install is due to updating a disabled theme.
   // |pending_install_id_| should be set to |kDefaultThemeID| if there are no
   // recently installed theme extensions
   std::string installed_pending_load_id_;
 
   // The number of infobars currently displayed.
   int number_of_infobars_;
 
+  // A cache of already-computed values for COLOR_TOOLBAR_TOP_SEPARATOR, which
+  // can be expensive to compute.
+  mutable SeparatorColorCache separator_color_cache_;
+
   content::NotificationRegistrar registrar_;
 
   scoped_ptr<ThemeSyncableService> theme_syncable_service_;
 
 #if defined(ENABLE_EXTENSIONS)
   class ThemeObserver;
   scoped_ptr<ThemeObserver> theme_observer_;
 #endif
 
   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_