Add app.window.alphaEnabled() and onAlphaEnabledChanged.

apps/ui/views/native_app_window_views.cc

 // Copyright 2014 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 "apps/ui/views/native_app_window_views.h"
 
 #include "apps/app_window.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/common/draggable_region.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/gfx/path.h"
 #include "ui/views/controls/webview/webview.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/window/non_client_view.h"
 
 #if defined(USE_AURA)
 #include "ui/aura/window.h"
 #endif
 
 namespace apps {
 
 NativeAppWindowViews::NativeAppWindowViews()
     : app_window_(NULL),
       web_view_(NULL),
       widget_(NULL),
       frameless_(false),
-      transparent_background_(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;
   resizable_ = create_params.resizable;
   size_constraints_.set_minimum_size(
       create_params.GetContentMinimumSize(gfx::Insets()));
   size_constraints_.set_maximum_size(
       create_params.GetContentMaximumSize(gfx::Insets()));
   Observe(app_window_->web_contents());
 
   widget_ = new views::Widget;
   InitializeWindow(app_window, create_params);
 
@@ skipping 205 matching lines @@
                                                      bool active) {
   app_window_->OnNativeWindowChanged();
   if (active)
     app_window_->OnNativeWindowActivated();
 }
 
 // WebContentsObserver implementation.
 
 void NativeAppWindowViews::RenderViewCreated(
     content::RenderViewHost* render_view_host) {
-  if (transparent_background_) {
+  if (app_window_->RequestedTransparentBackground() && CanHaveAlphaEnabled()) {
     content::RenderWidgetHostView* view = render_view_host->GetView();
     DCHECK(view);
     view->SetBackgroundOpaque(false);
   }
 }
 
 void NativeAppWindowViews::RenderViewHostChanged(
     content::RenderViewHost* old_host,
     content::RenderViewHost* new_host) {
   OnViewWasResized();
@@ skipping 117 matching lines @@
 gfx::Size NativeAppWindowViews::GetContentMaximumSize() const {
   return size_constraints_.GetMaximumSize();
 }
 
 void NativeAppWindowViews::SetContentSizeConstraints(
     const gfx::Size& min_size, const gfx::Size& max_size) {
   size_constraints_.set_minimum_size(min_size);
   size_constraints_.set_maximum_size(max_size);
 }
 
+bool NativeAppWindowViews::CanHaveAlphaEnabled() const {
+  return true;

[tapted, 2014/07/14 03:30:24]

does this work fine on desktop-linux as well as ChromeOS? I thought we were
still missing things for the general case there..

[jackhou1, 2014/07/14 04:51:02]

This doesn't work on Linux. 

I think this logic should live in the tree host, but I'm not sure what's the
right way to pipe it back up to the NativeAppWindow. What's in this patch set
obviously doesn't work though, so I'll implement it in a way that works (add
CanHaveAlphaEnabled to Widget and WindowTreeHost) and wait for benwells'
comments.

+}
+
+void NativeAppWindowViews::CanHaveAlphaEnabledChanged() {
+  app_window_->OnNativeWindowChanged();
+}
+
 }  // namespace apps