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"
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
+namespace {
+
+// Hardcoded colors for use when there is no system theme (Aura, ChromeOS).
+const SkColor kDefaultDialogBackgroundColor = SkColorSetRGB(200, 200, 200);
+const SkColor kInvalidColorIdColor = SkColorSetRGB(255, 0, 128);
+
+}  // namespace
+
 namespace gfx {
 
 unsigned int NativeThemeBase::button_length_ = 14;
 #if defined(TOUCH_UI)
 unsigned int NativeThemeBase::scrollbar_width_ = 0;
 #else
 unsigned int NativeThemeBase::scrollbar_width_ = 15;
 #endif
 
 // These are the default dimensions of radio buttons and checkboxes.
@@ skipping 300 matching lines @@
     case kTrackbarTrack:
     case kWindowResizeGripper:
       NOTIMPLEMENTED();
       break;
     default:
       NOTREACHED() << "Unknown theme part: " << part;
       break;
   }
 }
 
+SkColor NativeThemeBase::GetSystemColor(ColorId color_id) const {
+  // This implementation returns hardcoded colors. It's used by NativeThemeAura
+  // and NativeThemeChromeos and overridden by NativeThemeGtk.
+  switch (color_id) {
+    case kColorId_DialogBackground:
+      return kDefaultDialogBackgroundColor;
+    default:
+      NOTREACHED() << "Invalid color_id: " << color_id;
+      break;
+  }
+  return kInvalidColorIdColor;
+}
+
 void NativeThemeBase::PaintScrollbarTrack(SkCanvas* canvas,
     Part part,
     State state,
     const ScrollbarTrackExtraParams& extra_params,
     const gfx::Rect& rect) const {
   SkPaint paint;
   SkIRect skrect;
 
   skrect.set(rect.x(), rect.y(), rect.right(), rect.bottom());
   SkScalar track_hsv[3];
@@ skipping 638 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