Make Page Visibility API work when the browser window is visible or not

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 63c1609fa100e62bb3bdcdbd4d8c79807e5283ec..1e5acc19ac0eaeda043404fc45da2967108d8f0c 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -608,7 +608,13 @@ void RenderWidgetHostViewAura::Show() {
 }
 
 void RenderWidgetHostViewAura::Hide() {
-  window_->Hide();
+  Hide(false);
+}
+
+void RenderWidgetHostViewAura::Hide(bool content_visible) {
+  // We need to show content in a workspace view like Mac OSX Expose.
+  if (!content_visible)
+    window_->Hide();
 
   if (host_ && !host_->is_hidden()) {
     host_->WasHidden();