Mac: Update zoom bubble UI

ui/native_theme/native_theme_mac.mm

Index: ui/native_theme/native_theme_mac.mm
diff --git a/ui/native_theme/native_theme_mac.mm b/ui/native_theme/native_theme_mac.mm
new file mode 100644
index 0000000000000000000000000000000000000000..c3152a8d14582fcd4275d808283e813769e68e6c
--- /dev/null
+++ b/ui/native_theme/native_theme_mac.mm
@@ -0,0 +1,51 @@
+// Copyright (c) 2013 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/native_theme/native_theme_mac.h"
+
+#include "base/basictypes.h"
+#include "ui/native_theme/common_theme.h"
+
+namespace {
+
+const SkColor kInvalidColorIdColor = SkColorSetRGB(255, 0, 128);
+const SkColor kDialogBackgroundColor = SkColorSetRGB(251, 251, 251);
+
+}  // namespace
+
+namespace ui {
+
+// static
+NativeTheme* NativeTheme::instance() {
+  return NativeThemeMac::instance();
+}
+
+// static
+NativeThemeMac* NativeThemeMac::instance() {
+  CR_DEFINE_STATIC_LOCAL(NativeThemeMac, s_native_theme, ());
+  return &s_native_theme;
+}
+
+SkColor NativeThemeMac::GetSystemColor(ColorId color_id) const {
+  SkColor color;
+  if (CommonThemeGetSystemColor(color_id, &color))
+    return color;
+
+  switch (color_id) {
+    case kColorId_DialogBackground:
+      return kDialogBackgroundColor;
+    default:
+      NOTREACHED() << "Invalid color_id: " << color_id;
+  }
+
+  return kInvalidColorIdColor;
+}
+
+NativeThemeMac::NativeThemeMac() {
+}
+
+NativeThemeMac::~NativeThemeMac() {
+}
+
+}  // namespace ui