Fixes crash in launcher. Some tests don't end up creating a delegate,

ui/aura_shell/launcher/launcher_view.cc

Index: ui/aura_shell/launcher/launcher_view.cc
diff --git a/ui/aura_shell/launcher/launcher_view.cc b/ui/aura_shell/launcher/launcher_view.cc
index 7847f7712ccf0dfdf661f56875139db9d4d929f3..0f78a9b7c9efed68166d212b648b82e86855ca24 100644
--- a/ui/aura_shell/launcher/launcher_view.cc
+++ b/ui/aura_shell/launcher/launcher_view.cc
@@ -205,8 +205,10 @@ void LauncherView::Init() {
   model_->AddObserver(this);
   ResourceBundle& rb = ResourceBundle::GetSharedInstance();
   new_browser_button_ = new views::ImageButton(this);
-  int new_browser_button_image_id =
-      Shell::GetInstance()->delegate()->GetResourceIDForNewBrowserWindow();
+  ShellDelegate* delegate = Shell::GetInstance()->delegate();
+  int new_browser_button_image_id = delegate ?
+      delegate->GetResourceIDForNewBrowserWindow() :
+      IDR_AURA_LAUNCHER_ICON_CHROME;
   new_browser_button_->SetImage(
       views::CustomButton::BS_NORMAL,
       rb.GetImageNamed(new_browser_button_image_id).ToSkBitmap());