mash: improves browser frame decorations

ui/views/mus/desktop_window_tree_host_mus.cc

Index: ui/views/mus/desktop_window_tree_host_mus.cc
diff --git a/ui/views/mus/desktop_window_tree_host_mus.cc b/ui/views/mus/desktop_window_tree_host_mus.cc
index 3bd57d5dc174975b108ba1bb20130ecec810aab6..bdc12e227a91aa4fae2f0ae33a4b31bae696a856 100644
--- a/ui/views/mus/desktop_window_tree_host_mus.cc
+++ b/ui/views/mus/desktop_window_tree_host_mus.cc
@@ -276,9 +276,15 @@ bool DesktopWindowTreeHostMus::ShouldSendClientAreaToServer() const {
 
 void DesktopWindowTreeHostMus::Init(aura::Window* content_window,
                                     const Widget::InitParams& params) {
-  // Needed so we don't render over the non-client area the window manager
-  // renders to.
-  content_window->layer()->SetFillsBoundsOpaquely(false);
+  // |TYPE_WINDOW| and |TYPE_PANEL| are forced to transparent so that the
+  // window-manager draws the non-client area.

[James Cook, 2017/03/02 21:00:01]

Do we have to do it this way? I understand there's a pretty steep performance
cost to transparent windows. Or is this because we need rounded corners? If the
latter I'm confused by the comment.

[sky, 2017/03/02 21:28:42]

I updated the comment. Any better?

As to performance cost, in classic ash we make the window's layer transparent as
well
(https://chromium.googlesource.com/chromium/src/+/master/chrome/browser/ui/vie...).
It's certainly the case that there are more windows (and more layers) in mash.
No doubt we will have to revisit this. Sadrul has been looking at performance,
so it is in people's minds.

[James Cook, 2017/03/02 21:44:24]

Better!

+  const bool transparent =
+      params.opacity == Widget::InitParams::TRANSLUCENT_WINDOW ||
+      params.type == Widget::InitParams::TYPE_WINDOW ||
+      params.type == Widget::InitParams::TYPE_PANEL;
+  content_window->SetTransparent(transparent);
+  window()->SetTransparent(transparent);
+
   if (!params.bounds.IsEmpty())
     SetBoundsInDIP(params.bounds);
 
@@ -305,6 +311,9 @@ void DesktopWindowTreeHostMus::Init(aura::Window* content_window,
 
 void DesktopWindowTreeHostMus::OnNativeWidgetCreated(
     const Widget::InitParams& params) {
+  window()->SetName(params.name);
+  desktop_native_widget_aura_->content_window()->SetName(
+      "DesktopNativeWidgetAura - content window");
   if (params.parent && params.parent->GetHost()) {
     parent_ = static_cast<DesktopWindowTreeHostMus*>(params.parent->GetHost());
     parent_->children_.insert(this);