mash: Migrate ShelfTooltipManager to wm common types.

ash/common/wm_window.h

Index: ash/common/wm_window.h
diff --git a/ash/common/wm_window.h b/ash/common/wm_window.h
index d371caead22e5ad3f4c826a9cfa006a047eb6b7d..7d748a3cb96fb4da2e59eb66791ede8cb0fa39de 100644
--- a/ash/common/wm_window.h
+++ b/ash/common/wm_window.h
@@ -28,6 +28,7 @@ class Transform;
 }
 
 namespace ui {
+class EventHandler;
 class Layer;
 }
 
@@ -45,7 +46,6 @@ class WmWindowObserver;
 enum class WmWindowProperty;
 
 namespace wm {
-class WMEvent;
 class WindowState;
 }
 
@@ -284,6 +284,11 @@ class ASH_EXPORT WmWindow {
   virtual void RemoveObserver(WmWindowObserver* observer) = 0;
   virtual bool HasObserver(const WmWindowObserver* observer) const = 0;
 
+  // Adds or removes a handler to receive events before this window; the handler
+  // does not recieve events from embedded windows. Does not transfer ownership.

[sky, 2016/07/26 13:25:20]

Also document this only receives events targetted at just this window.

[msw, 2016/07/26 17:43:25]

Updated w/"targeted at this window", lmk if you have something better in mind.

+  virtual void AddLimitedPreTargetHandler(ui::EventHandler* handler) = 0;
+  virtual void RemoveLimitedPreTargetHandler(ui::EventHandler* handler) = 0;
+
  protected:
   virtual ~WmWindow() {}
 };