position the balloons after closing in a way that will keep the next one's cl...

chrome/browser/notifications/balloon_collection_impl.h

Index: chrome/browser/notifications/balloon_collection_impl.h
===================================================================
--- chrome/browser/notifications/balloon_collection_impl.h	(revision 52083)
+++ chrome/browser/notifications/balloon_collection_impl.h	(working copy)
@@ -10,20 +10,34 @@
 #include <deque>
 
 #include "base/basictypes.h"
+#include "base/message_loop.h"
 #include "chrome/browser/notifications/balloon_collection.h"
 #include "gfx/point.h"
 #include "gfx/rect.h"
 
+// Mac balloons grow from the top down and have close buttons on top, so
+// offsetting is not necessary for easy multiple-closing.  Other platforms grow
+// from the bottom up and have close buttons on top, so it is necessary.
+#if defined(OS_MACOSX)
+#define USE_OFFSETS 0
+#else
+#define USE_OFFSETS 1
+#endif
+
 // A balloon collection represents a set of notification balloons being
 // shown on the screen.  It positions new notifications according to
 // a layout, and monitors for balloons being closed, which it reports
 // up to its parent, the notification UI manager.
-class BalloonCollectionImpl : public BalloonCollection {
+class BalloonCollectionImpl : public BalloonCollection
+#if USE_OFFSETS
+                            , public MessageLoopForUI::Observer
+#endif
+{
  public:
   BalloonCollectionImpl();
   virtual ~BalloonCollectionImpl();
 
-  // BalloonCollectionInterface overrides
+  // BalloonCollection interface.
   virtual void Add(const Notification& notification,
                    Profile* profile);
   virtual bool Remove(const Notification& notification);
@@ -35,6 +49,16 @@
     return balloons_;
   }
 
+  // MessageLoopForUI::Observer interface.
+#if defined(OS_WIN)
+  virtual void WillProcessMessage(const MSG& event) {}
+  virtual void DidProcessMessage(const MSG& event);
+#endif
+#if defined(OS_LINUX)
+  virtual void WillProcessEvent(GdkEvent* event) {}
+  virtual void DidProcessEvent(GdkEvent* event);
+#endif
+
  protected:
   // Calculates layout values for the balloons including
   // the scaling, the max/min sizes, and the upper left corner of each.
@@ -121,6 +145,21 @@
   static gfx::Rect GetMacWorkArea();
 #endif
 
+#if USE_OFFSETS
+  // Start and stop observing all UI events.
+  void AddMessageLoopObserver();
+  void RemoveMessageLoopObserver();
+
+  // Cancel all offset and reposition the balloons normally.
+  void CancelOffsets();
+
+  // Handles a mouse motion while the balloons are temporarily offset.
+  void HandleMouseMoveEvent();
+
+  // Is the current cursor in the balloon area?
+  bool IsCursorInBalloonCollection() const;
+#endif
+
   // Queue of active balloons.
   typedef std::deque<Balloon*> Balloons;
   Balloons balloons_;
@@ -128,6 +167,14 @@
   // The layout parameters for balloons in this collection.
   Layout layout_;
 
+#if USE_OFFSETS
+  // Factory for generating delayed reposition tasks on mouse motion.
+  ScopedRunnableMethodFactory<BalloonCollectionImpl> reposition_factory_;
+
+  // Is the balloon collection currently listening for UI events?
+  bool added_as_message_loop_observer_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
 };