Enable shelf gestures in immersive mode

ash/wm/gestures/shelf_gesture_handler.cc

Index: ash/wm/gestures/shelf_gesture_handler.cc
diff --git a/ash/wm/gestures/shelf_gesture_handler.cc b/ash/wm/gestures/shelf_gesture_handler.cc
index aba69fd9e803655ceafbb3cb91cd0cb5969c96fc..2d3e9b99a5e40de57ab66e85594fea98c70a3698 100644
--- a/ash/wm/gestures/shelf_gesture_handler.cc
+++ b/ash/wm/gestures/shelf_gesture_handler.cc
@@ -12,6 +12,7 @@
 #include "ash/shell.h"
 #include "ash/system/status_area_widget.h"
 #include "ash/wm/gestures/tray_gesture_handler.h"
+#include "ash/wm/window_properties.h"
 #include "ash/wm/window_util.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
@@ -37,14 +38,17 @@ bool ShelfGestureHandler::ProcessGestureEvent(const ui::GestureEvent& event) {
     return false;
   }
 
-  // The gesture are disabled for fullscreen windows.
-  aura::Window* active = wm::GetActiveWindow();
-  if (active && wm::IsWindowFullscreen(active))
+  // TODO(oshima): Find the root window controller from event's location.
+  RootWindowController* controller = Shell::GetPrimaryRootWindowController();
+
+  ShelfLayoutManager* shelf = controller->GetShelfLayoutManager();
+
+  // The gesture are disabled for fullscreen windows that are not in immersive
+  // mode.
+  aura::Window* fullscreen = controller->GetFullscreenWindow();
+  if (fullscreen && !shelf->FullscreenWithMinimalChrome())
     return false;
 
-  // TODO(oshima): Find the root window controller from event's location.
-  ShelfLayoutManager* shelf =
-      Shell::GetPrimaryRootWindowController()->GetShelfLayoutManager();
   if (event.type() == ui::ET_GESTURE_SCROLL_BEGIN) {
     drag_in_progress_ = true;
     shelf->StartGestureDrag(event);