Revert of Rename wm_core_export.h to wm_export.h and the wm_core target to just wm

ui/wm/core/transient_window_manager.h

Index: ui/wm/core/transient_window_manager.h
diff --git a/ui/wm/core/transient_window_manager.h b/ui/wm/core/transient_window_manager.h
index 7d37679f924d0cbf8b6b684b92eaa2430b3f518a..350bb1a294e412616b8ba49daa3a4c1d56888544 100644
--- a/ui/wm/core/transient_window_manager.h
+++ b/ui/wm/core/transient_window_manager.h
@@ -9,7 +9,7 @@
 
 #include "base/observer_list.h"
 #include "ui/aura/window_observer.h"
-#include "ui/wm/wm_export.h"
+#include "ui/wm/core/wm_core_export.h"
 
 namespace wm {
 
@@ -26,7 +26,7 @@
 // Transient windows are typically used for popups and menus.
 // TODO(sky): when we nuke TransientWindowClient rename this to
 // TransientWindowController.
-class WM_EXPORT TransientWindowManager : public aura::WindowObserver {
+class WM_CORE_EXPORT TransientWindowManager : public aura::WindowObserver {
  public:
   typedef std::vector<aura::Window*> Windows;