Fix gtk3 build

chrome/browser/ui/libgtk2ui/gtk2_ui.cc

Index: chrome/browser/ui/libgtk2ui/gtk2_ui.cc
diff --git a/chrome/browser/ui/libgtk2ui/gtk2_ui.cc b/chrome/browser/ui/libgtk2ui/gtk2_ui.cc
index a3a2b5de040d3392e4500e47c81232eb2c7bdf6c..ef6b7c012ecc44d88db50ffb0d849a1d56e2284d 100644
--- a/chrome/browser/ui/libgtk2ui/gtk2_ui.cc
+++ b/chrome/browser/ui/libgtk2ui/gtk2_ui.cc
@@ -243,7 +243,11 @@ const color_utils::HSL kDefaultTintFrameIncognitoInactive = { -1, 0.3f, 0.6f };
 
 #if GTK_MAJOR_VERSION == 3
 const color_utils::HSL kDefaultTintFrameInactive = { -1, -1, 0.75f };
-#endif
+
+// The size of the rendered toolbar image.
+const int kToolbarImageWidth = 64;
+const int kToolbarImageHeight = 128;
+#endif  // GTK_MAJOR_VERSION == 3
 
 // Picks a button tint from a set of background colors. While
 // |accent_color| will usually be the same color through a theme, this