Transparent apps support

chrome/browser/ui/views/extensions/shell_window_views.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/ui/views/extensions/shell_window_views.h"
 
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 #include "chrome/browser/ui/views/extensions/extension_keybinding_registry_views.h"
@@ skipping 376 matching lines @@
     frame_->Restore();
   else if (sender == minimize_button_)
     frame_->Minimize();
 }
 
 ShellWindowViews::ShellWindowViews(ShellWindow* shell_window,
                                    const ShellWindow::CreateParams& win_params)
     : 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;
   params.remove_standard_frame = true;
   params.use_system_default_icon = true;

[sky, 2012/11/08 16:29:10]

Don't you also need to set params.transparent? And similarly what about the
native view created by WebContents?

[Bernie, 2012/12/18 21:08:36]

The helloworld demo app gets a transparent background without doing anything
else.

InitParams seems to infer transparency from UseTransparentWindows(), which
always returns true on OS_CHROMEOS.

   minimum_size_ = win_params.minimum_size;
   maximum_size_ = win_params.maximum_size;
   window_->Init(params);
   gfx::Rect window_bounds =
       window_->non_client_view()->GetWindowBoundsForClientBounds(
           win_params.bounds);
   // Center window if no position was specified.
   if (win_params.bounds.x() == INT_MIN || win_params.bounds.y() == INT_MIN) {
     window_->CenterWindow(window_bounds.size());
   } else {
@@ skipping 270 matching lines @@
 }
 
 bool ShellWindowViews::ShouldShowWindowTitle() const {
   return false;
 }
 
 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());
   OnViewWasResized();
 }
 
 void ShellWindowViews::UpdateWindowIcon() {
   window_->UpdateWindowIcon();
 }
 
@@ skipping 25 matching lines @@
                                            ui::WindowShowState show_state) {
   views::WidgetDelegate::SaveWindowPlacement(bounds, show_state);
   shell_window_->SaveWindowPosition();
 }
 
 // static
 NativeShellWindow* NativeShellWindow::Create(
     ShellWindow* shell_window, const ShellWindow::CreateParams& params) {
   return new ShellWindowViews(shell_window, params);
 }