[cros] Add support for transparent background in sign in screen.

chrome/browser/chromeos/login/webui_login_view.cc

 // Copyright (c) 2012 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 "chrome/browser/chromeos/login/webui_login_view.h"
 
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
 #include "base/bind.h"
 #include "base/callback.h"
+#include "base/command_line.h"
 #include "base/i18n/rtl.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/chromeos/accessibility/accessibility_util.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
+#include "chrome/browser/chromeos/login/base_login_display_host.h"
 #include "chrome/browser/chromeos/login/proxy_settings_dialog.h"
 #include "chrome/browser/chromeos/login/webui_login_display.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/renderer_preferences_util.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
 #include "chrome/browser/ui/views/ash/chrome_shell_delegate.h"
 #include "chrome/browser/ui/webui/chromeos/login/oobe_ui.h"
 #include "chrome/common/chrome_notification_types.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/render_messages.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/session_manager_client.h"
 #include "content/public/browser/notification_service.h"
+#include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_view_host_observer.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 #include "ui/views/controls/webview/webview.h"
 #include "ui/views/widget/widget.h"
 
 using content::NativeWebKeyboardEvent;
 using content::RenderViewHost;
 using content::WebContents;
@@ skipping 157 matching lines @@
 
 void WebUILoginView::OnWindowCreated() {
 }
 
 void WebUILoginView::UpdateWindowType() {
 }
 
 void WebUILoginView::LoadURL(const GURL & url) {
   webui_login_->LoadInitialURL(url);
   webui_login_->RequestFocus();
+
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  // Only enable transparency on sign in screen, not on lock screen.
+  if (BaseLoginDisplayHost::default_host() &&
+      command_line->HasSwitch(switches::kEnableNewOobe)) {
+    // TODO(nkostylev): Use WebContentsObserver::RenderViewCreated to track
+    // when RenderView is created.
+    // Use a background with transparency to trigger transparency in Webkit.
+    SkBitmap background;
+    background.setConfig(SkBitmap::kARGB_8888_Config, 1, 1);
+    background.allocPixels();
+    background.eraseARGB(0x00, 0x00, 0x00, 0x00);
+    content::RenderViewHost* host =
+        wrapper_->web_contents()->GetRenderViewHost();
+    host->GetView()->SetBackground(background);
+  }
 }
 
 content::WebUI* WebUILoginView::GetWebUI() {
   return webui_login_->web_contents()->GetWebUI();
 }
 
 void WebUILoginView::OpenProxySettings() {
   ProxySettingsDialog* dialog =
       new ProxySettingsDialog(NULL, GetNativeWindow());
   dialog->Show();
@@ skipping 112 matching lines @@
   return true;
 }
 
 void WebUILoginView::ReturnFocus(bool reverse) {
   // Return the focus to the web contents.
   webui_login_->web_contents()->FocusThroughTabTraversal(reverse);
   GetWidget()->Activate();
 }
 
 }  // namespace chromeos