Gtk3: Add background class to tooltips

chrome/browser/ui/libgtkui/gtk_util.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_UI_LIBGTKUI_GTK_UTIL_H_
 #define CHROME_BROWSER_UI_LIBGTKUI_GTK_UTIL_H_
 
 #include <gtk/gtk.h>
 #include <string>
 
@@ skipping 148 matching lines @@
 // Parses |css_selector| into a GtkStyleContext.  The format is a
 // sequence of whitespace-separated objects.  Each object may have at
 // most one object name at the beginning of the string, and any number
 // of '.'-prefixed classes and ':'-prefixed pseudoclasses.  An example
 // is "GtkButton.button.suggested-action:hover:active".  The caller
 // must g_object_unref() the returned context.
 ScopedStyleContext GetStyleContextFromCss(const std::string& css_selector);
 
 SkColor GetFgColorFromStyleContext(GtkStyleContext* context);
 
+SkColor GetBgColorFromStyleContext(GtkStyleContext* context);
+
 // Overrides properties on |context| and all its parents with those
 // provided by |css|.
 void ApplyCssToContext(GtkStyleContext* context, const std::string& css);
 
 // Get the 'color' property from the style context created by
 // GetStyleContextFromCss(|css_selector|).
 SkColor GetFgColor(const std::string& css_selector);
 
 ScopedCssProvider GetCssProvider(const std::string& css);
 
@@ skipping 17 matching lines @@
 // the background-color property.
 SkColor GetSelectionBgColor(const std::string& css_selector);
 
 // Get the color of the GtkSeparator specified by |css_selector|.
 SkColor GetSeparatorColor(const std::string& css_selector);
 #endif
 
 }  // namespace libgtkui
 
 #endif  // CHROME_BROWSER_UI_LIBGTKUI_GTK_UTIL_H_