Don't set DesktopNativeWidgetAura's window transparent if not necessary.

If it's not using the native frame (e.g. on XP), the window doesn't need to be transparent, which saves a clear before painting its contents.

BUG=
R=ben@chromium.org

Review URL: https://codereview.chromium.org/24941002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225781 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 11 insertions, 1 deletions

diff --git a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
index 7dd3dfe..698a342 100644
--- a/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
+++ b/ui/views/widget/desktop_aura/desktop_native_widget_aura.cc
@@ -283,7 +283,6 @@ void DesktopNativeWidgetAura::InitNativeWidget(
     window_->SetProperty(aura::client::kAnimationsDisabledKey, true);
   }
   window_->SetType(GetAuraWindowTypeForWidgetType(params.type));
-  window_->SetTransparent(true);
   window_->Init(params.layer_type);
   corewm::SetShadowType(window_, corewm::SHADOW_TYPE_NONE);
 #if defined(OS_LINUX)  // TODO(scottmg): http://crbug.com/180071
@@ -297,6 +296,8 @@ void DesktopNativeWidgetAura::InitNativeWidget(
   root_window_.reset(
       desktop_root_window_host_->Init(window_, params));
 
+  UpdateWindowTransparency();
+
   content_window_container_ = new aura::Window(NULL);
   content_window_container_->Init(ui::LAYER_NOT_DRAWN);
   content_window_container_->Show();
@@ -353,6 +354,7 @@ bool DesktopNativeWidgetAura::ShouldUseNativeFrame() const {
 
 void DesktopNativeWidgetAura::FrameTypeChanged() {
   desktop_root_window_host_->FrameTypeChanged();
+  UpdateWindowTransparency();
 }
 
 Widget* DesktopNativeWidgetAura::GetWidget() {
@@ -975,4 +977,8 @@ ui::EventHandler* DesktopNativeWidgetAura::GetEventHandler() {
   return this;
 }
 
+void DesktopNativeWidgetAura::UpdateWindowTransparency() {
+  window_->SetTransparent(ShouldUseNativeFrame());
+}
+
 }  // namespace views
diff --git a/ui/views/widget/desktop_aura/desktop_native_widget_aura.h b/ui/views/widget/desktop_aura/desktop_native_widget_aura.h
index b644e7c..c1c97a0 100644
--- a/ui/views/widget/desktop_aura/desktop_native_widget_aura.h
+++ b/ui/views/widget/desktop_aura/desktop_native_widget_aura.h
@@ -218,6 +218,10 @@ class VIEWS_EXPORT DesktopNativeWidgetAura
       const aura::RootWindow* root) OVERRIDE;
 
  private:
+  // To save a clear on platforms where the window is never transparent, the
+  // window is only set as transparent when the glass frame is in use.
+  void UpdateWindowTransparency();
+
   // See class documentation for Widget in widget.h for a note about ownership.
   Widget::InitParams::Ownership ownership_;