Smooth Tab Switching on aura.

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 1a8db6dc1241cc986caeb29af4cfc1677de1a054..90ff55c148f113ab97316db02df93a3f81390447 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -283,10 +283,14 @@ RenderWidgetHost* RenderWidgetHostViewAura::GetRenderWidgetHost() const {
 
 void RenderWidgetHostViewAura::DidBecomeSelected() {
   host_->WasRestored();
+  if (!current_surface_ && host_->is_accelerated_compositing_active() &&
+      !released_front_lock_.get())
+    released_front_lock_ = window_->GetRootWindow()->GetCompositorLock();
 }
 
 void RenderWidgetHostViewAura::WasHidden() {
   host_->WasHidden();
+  released_front_lock_ = NULL;
 }
 
 void RenderWidgetHostViewAura::SetSize(const gfx::Size& size) {
@@ -509,6 +513,8 @@ void RenderWidgetHostViewAura::UpdateExternalTexture() {
       container->Update();
     window_->SetExternalTexture(container);
 
+    released_front_lock_ = NULL;
+
     if (!container) {
       resize_locks_.clear();
     } else {