Call aura::Env::CreateInstance in ExamplesBrowserMainParts::PreMainMessageLoopRun.

BUG=313848
TEST=views_examples_with_content_exe runs in Win Aura.
R=ben@chromium.org

Review URL: https://codereview.chromium.org/49533005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232962 0039d316-1c4b-4281-b951-d872f2087c98

ui/views/examples/content_client/examples_browser_main_parts.cc

@@ -55,6 +55,7 @@ void ExamplesBrowserMainParts::PreMainMessageLoopRun() {
   // Ensure Aura knows where to open new windows.
   window_context = minimal_shell_->root_window();
 #elif defined(USE_AURA)
+  aura::Env::CreateInstance();
   gfx::Screen::SetScreenInstance(
       gfx::SCREEN_TYPE_NATIVE, CreateDesktopScreen());
 #endif