Add an aura window property for Immersive fullscreen mode

ash/common/wm_window.cc

Index: ash/common/wm_window.cc
diff --git a/ash/common/wm_window.cc b/ash/common/wm_window.cc
index 0cdaf6b7d6ef0b89c8b8653725bfd7ebc73f340a..f7e86e1ed49bda6b80f80ef83918798d38ccde5b 100644
--- a/ash/common/wm_window.cc
+++ b/ash/common/wm_window.cc
@@ -937,6 +937,11 @@ void WmWindow::OnWindowPropertyChanged(aura::Window* window,
     ash::wm::GetWindowState(window_)->OnWindowShowStateChanged();
     return;
   }
+  if (key == aura::client::kImmersiveFullscreenKey) {

[sky, 2017/01/25 17:42:12]

The description doesn't match usage of the property. You describe the property
as if fullscreen should be treated as immersive, where as setting the value here
means the window is in immersive now.

[Peng, 2017/01/25 19:02:38]

See [1], the in_immersive_fullscreen() is only useful when the window is
fullscreen. So probably in_immersive_fullscreen() should be renamed to
is_immersive_fullscreen() to match its usage.

[1]
https://cs.chromium.org/chromium/src/ash/common/wm/maximize_mode/maximize_mod...

+    bool enable = window_->GetProperty(aura::client::kImmersiveFullscreenKey);
+    GetWindowState()->set_in_immersive_fullscreen(enable);
+    return;
+  }
   WmWindowProperty wm_property;
   if (key == aura::client::kAlwaysOnTopKey) {
     wm_property = WmWindowProperty::ALWAYS_ON_TOP;