Add support for transparent background API

apps/ui/views/native_app_window_views.cc

Index: apps/ui/views/native_app_window_views.cc
diff --git a/apps/ui/views/native_app_window_views.cc b/apps/ui/views/native_app_window_views.cc
index 22c384e43ac686b2ad7f95d7b5f8d2e2c9e1df33..8eefdb5e082537a3b8606ff1101f42abb6df905a 100644
--- a/apps/ui/views/native_app_window_views.cc
+++ b/apps/ui/views/native_app_window_views.cc
@@ -27,14 +27,15 @@ NativeAppWindowViews::NativeAppWindowViews()
       web_view_(NULL),
       widget_(NULL),
       frameless_(false),
-      transparent_background_(false),
-      resizable_(false) {}
+      alpha_enabled_(false),
+      resizable_(false) {
+}
 
 void NativeAppWindowViews::Init(AppWindow* app_window,
                                 const AppWindow::CreateParams& create_params) {
   app_window_ = app_window;
   frameless_ = create_params.frame == AppWindow::FRAME_NONE;
-  transparent_background_ = create_params.transparent_background;
+  alpha_enabled_ = create_params.alpha_enabled;
   resizable_ = create_params.resizable;
   size_constraints_.set_minimum_size(
       create_params.GetContentMinimumSize(gfx::Insets()));
@@ -261,7 +262,7 @@ void NativeAppWindowViews::OnWidgetActivationChanged(views::Widget* widget,
 
 void NativeAppWindowViews::RenderViewCreated(
     content::RenderViewHost* render_view_host) {
-  if (transparent_background_) {
+  if (alpha_enabled_) {
     // Use a background with transparency to trigger transparency in Webkit.
     SkBitmap background;
     background.setConfig(SkBitmap::kARGB_8888_Config, 1, 1);