Back button should be able to close apps

sky/shell/shell_view.cc

Index: sky/shell/shell_view.cc
diff --git a/sky/shell/shell_view.cc b/sky/shell/shell_view.cc
index bbcd069a3ab91b57b8f6d9f4863a2098cf45988d..bb83d422ef2491f65a67d1ea652adf3fe65c6957 100644
--- a/sky/shell/shell_view.cc
+++ b/sky/shell/shell_view.cc
@@ -13,6 +13,12 @@
 
 namespace sky {
 namespace shell {
+namespace {
+
+template<typename T>
+void Drop(scoped_ptr<T> ptr) { }
+
+}  // namespace
 
 ShellView::ShellView(Shell& shell)
     : shell_(shell) {
@@ -22,6 +28,10 @@ ShellView::ShellView(Shell& shell)
 }
 
 ShellView::~ShellView() {
+  shell_.gpu_task_runner()->PostTask(FROM_HERE,
+      base::Bind(&Drop<Rasterizer>, base::Passed(&rasterizer_)));
+  shell_.ui_task_runner()->PostTask(FROM_HERE,
+      base::Bind(&Drop<Engine>, base::Passed(&engine_)));
 }
 
 void ShellView::CreateEngine() {