fix for 156227, 153077, 134093

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 3584a2f4487f1004e0002fd77d5d4cefae019dbc..83afc255dd8502554fff0d05ab92144d606f4f7b 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -186,7 +186,8 @@ Shell::Shell(ShellDelegate* delegate)
       output_configurator_animation_(
           new internal::OutputConfiguratorAnimation()),
 #endif  // defined(OS_CHROMEOS)
-      browser_context_(NULL) {
+      browser_context_(NULL),
+      simulate_modal_window_open_for_testing_(false) {
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, screen_.get());
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_ALTERNATE, screen_.get());
   ui_controls::InstallUIControlsAura(internal::CreateUIControls());
@@ -538,6 +539,8 @@ bool Shell::IsScreenLocked() const {
 }
 
 bool Shell::IsModalWindowOpen() const {
+  if (simulate_modal_window_open_for_testing_)
+    return true;
   // TODO(oshima): Walk though all root windows.
   const aura::Window* modal_container = GetContainer(
       GetPrimaryRootWindow(),