Add a new GetSystemColor method to native theme.

ui/gfx/native_theme_base.cc

 // Copyright (c) 2011 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 "ui/gfx/native_theme_base.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "grit/gfx_resources.h"
@@ skipping 39 matching lines @@
 
   return color_utils::HSLToSkColor(adjusted, alpha);
 }
 
 NativeThemeBase::NativeThemeBase() {
 }
 
 NativeThemeBase::~NativeThemeBase() {
 }
 
+// This implementation returns hardcoded colors. It's used by NativeThemeAura
+// and NativeThemeChromeos and overridden by NativeThemeGtk.
+SkColor NativeThemeBase::GetSystemColor(ColorId color_id) const {
+  switch (color_id) {
+    case kDialogBackgroundColor:
+      return SkColorSetRGB(200, 200, 200);

[James Cook, 2011/11/18 23:22:50]

We typically define colors like this as constants in an anonymous namespace,
like:

namespace {

const SkColor kDialogBackgroundColor = ...;

}

even if they are used only once.  That also might imply that the enum should be
named kDialogBackground or kDialogBackgroundColorId or some such.

[benrg, 2011/11/19 00:20:22]

Done.

+    default:
+      NOTREACHED() << "Invalid color_id: " << color_id;
+      break;
+  }
+  return SkColorSetRGB(255, 0, 0);  // warning red
+}
+
 gfx::Size NativeThemeBase::GetPartSize(Part part,
                                        State state,
                                        const ExtraParams& extra) const {
   switch (part) {
     // Please keep these in the order of NativeTheme::Part.
     case kCheckbox:
       return gfx::Size(kCheckboxAndRadioWidth, kCheckboxAndRadioHeight);
     case kInnerSpinButton:
       return gfx::Size(scrollbar_width_, 0);
     case kMenuList:
@@ skipping 915 matching lines @@
   SkScalar min_diff = Clamp((hsv1[1] + hsv2[1]) * 1.2f, 0.28f, 0.5f);
   SkScalar diff = Clamp(fabs(hsv1[2] - hsv2[2]) / 2, min_diff, 0.5f);
 
   if (hsv1[2] + hsv2[2] > 1.0)
     diff = -diff;
 
   return SaturateAndBrighten(hsv2, -0.2f, diff);
 }
 
 }  // namespace gfx