Proper MouseEvent targeting. Adds a Window method that locates a Window for a given point.

aura/event.h

Index: aura/event.h
===================================================================
--- aura/event.h	(revision 98650)
+++ aura/event.h	(working copy)
@@ -21,6 +21,8 @@
 typedef XEvent* NativeEvent;
 #endif
 
+class Window;
+
 class Event {
  public:
   const NativeEvent& native_event() const { return native_event_; }
@@ -55,6 +57,11 @@
  protected:
   explicit LocatedEvent(NativeEvent native_event);
 
+  // Create a new LocatedEvent which is identical to the provided model.
+  // If source / target windows are provided, the model location will be
+  // converted from |source| coordinate system to |target| coordinate system.
+  LocatedEvent(const LocatedEvent& model, Window* source, Window* target);
+
   gfx::Point location_;
 
  private:
@@ -65,6 +72,11 @@
  public:
   explicit MouseEvent(NativeEvent native_event);
 
+  // Create a new MouseEvent which is identical to the provided model.
+  // If source / target windows are provided, the model location will be
+  // converted from |source| coordinate system to |target| coordinate system.
+  MouseEvent(const MouseEvent& model, Window* source, Window* target);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(MouseEvent);
 };