gtk3: Fix compile by readding a constant.

chrome/browser/ui/libgtk2ui/gtk2_ui.cc

 // 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.
 
 #include "chrome/browser/ui/libgtk2ui/gtk2_ui.h"
 
 #include <math.h>
 #include <pango/pango.h>
 #include <set>
 #include <utility>
@@ skipping 294 matching lines @@
 
 // TODO(erg): ThemeService has a whole interface just for reading default
 // constants. Figure out what to do with that more long term; for now, just
 // copy the constants themselves here.
 //
 // Default tints.
 const color_utils::HSL kDefaultTintFrameIncognito = { -1, 0.2f, 0.35f };
 const color_utils::HSL kDefaultTintFrameIncognitoInactive = { -1, 0.3f, 0.6f };
 const color_utils::HSL kDefaultTintBackgroundTab = { -1, 0.5, 0.75 };
 
+#if GTK_MAJOR_VERSION == 3
+const color_utils::HSL kDefaultTintFrameInactive = { -1, -1, 0.75f };
+#endif
+
 // Picks a button tint from a set of background colors. While
 // |accent_color| will usually be the same color through a theme, this
 // function will get called with the normal GtkLabel |text_color|/GtkWindow
 // |background_color| pair and the GtkEntry |text_color|/|background_color|
 // pair. While 3/4 of the time the resulting tint will be the same, themes that
 // have a dark window background (with light text) and a light text entry (with
 // dark text) will get better icons with this separated out.
 void PickButtonTintFromColors(SkColor accent_color,
                               SkColor text_color,
                               SkColor background_color,
@@ skipping 1035 matching lines @@
   // Blacklist scaling factors <130% (crbug.com/484400) and round
   // to 1 decimal to prevent rendering problems (crbug.com/485183).
   return scale < 1.3f ? 1.0f : roundf(scale * 10) / 10;
 }
 
 }  // namespace libgtk2ui
 
 views::LinuxUI* BuildGtk2UI() {
   return new libgtk2ui::Gtk2UI;
 }