Transparent apps support

chrome/browser/ui/views/extensions/shell_window_views.cc

Index: chrome/browser/ui/views/extensions/shell_window_views.cc
diff --git a/chrome/browser/ui/views/extensions/shell_window_views.cc b/chrome/browser/ui/views/extensions/shell_window_views.cc
index cadd16b9102eb652df7c30bb8d7e872938162c53..4ee7994b024112ed2727b5f3c3d2e7f5c066869a 100644
--- a/chrome/browser/ui/views/extensions/shell_window_views.cc
+++ b/chrome/browser/ui/views/extensions/shell_window_views.cc
@@ -394,7 +394,9 @@ ShellWindowViews::ShellWindowViews(ShellWindow* shell_window,
     : shell_window_(shell_window),
       web_view_(NULL),
       is_fullscreen_(false),
-      frameless_(win_params.frame == ShellWindow::CreateParams::FRAME_NONE) {
+      frameless_(win_params.frame == ShellWindow::CreateParams::FRAME_NONE),
+      transparent_background_(win_params.transparent_background) {
+  Observe(shell_window_->web_contents());
   window_ = new views::Widget;
   views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
   params.delegate = this;
@@ -690,6 +692,21 @@ void ShellWindowViews::OnWidgetMove() {
   shell_window_->SaveWindowPosition();
 }
 
+void ShellWindowViews::RenderViewCreated(
+    content::RenderViewHost* render_view_host) {
+  if (transparent_background_) {
+    // 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::RenderWidgetHostView* view = render_view_host->GetView();
+    DCHECK(view);
+    view->SetBackground(background);
+  }
+}
+
 void ShellWindowViews::Layout() {
   DCHECK(web_view_);
   web_view_->SetBounds(0, 0, width(), height());