Allow to have a transparent UA dependent background.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 6963b213ad3806a21bdf94826a1268a601d402f4..531bc42462486760e0f5ea6f02864d3774f9db90 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -958,6 +958,13 @@ void RenderWidgetHostViewAura::Focus() {
   aura::client::FocusClient* client = aura::client::GetFocusClient(window_);
   if (client)
     window_->Focus();
+
+  // XXX This is for testing, it has to be moved to a unit or browser test.
+  // Which would call:
+  // content::RenderWidgetHostView->SetBackgroundColor(SK_ColorTRANSPARENT)
+  // content::RenderWidgetHostView->SetBackgroundOpaque(true)
+  SetBackgroundColor(SK_ColorTRANSPARENT);
+  SetBackgroundOpaque(true);
 }
 
 bool RenderWidgetHostViewAura::HasFocus() const {
@@ -978,10 +985,14 @@ gfx::Rect RenderWidgetHostViewAura::GetViewBounds() const {
 
 void RenderWidgetHostViewAura::SetBackgroundColor(SkColor color) {
   RenderWidgetHostViewBase::SetBackgroundColor(color);
-  bool opaque = GetBackgroundOpaque();
+  host_->SetBackgroundColor(color);
+  window_->layer()->SetColor(color);
+}
+
+void RenderWidgetHostViewAura::SetBackgroundOpaque(bool opaque) {
+  RenderWidgetHostViewBase::SetBackgroundOpaque(opaque);
   host_->SetBackgroundOpaque(opaque);
   window_->layer()->SetFillsBoundsOpaquely(opaque);
-  window_->layer()->SetColor(color);
 }
 
 gfx::Size RenderWidgetHostViewAura::GetVisibleViewportSize() const {