Attempt 2 at:

views/widget/root_view.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "views/widget/root_view.h"
 
 #include <algorithm>
 
 #include "app/drag_drop_types.h"
 #include "base/keyboard_codes.h"
@@ skipping 471 matching lines @@
     mouse_move_handler_->OnMouseMoved(moved_event);
 
     gfx::NativeCursor cursor = mouse_move_handler_->GetCursorForPoint(
         moved_event.GetType(), moved_event.location());
     SetActiveCursor(cursor);
   } else if (mouse_move_handler_ != NULL) {
     MouseEvent exited_event(Event::ET_MOUSE_EXITED, 0, 0, 0);
     mouse_move_handler_->OnMouseExited(exited_event);
     SetActiveCursor(NULL);
   }
+
+  if (registered_near_views_.empty())
+    return;
+
+  std::set<View*> near_views;
+  GetViewsRegisteredForNearNotification(e, &near_views);
+
+  MouseEvent exited_near_event(Event::ET_MOUSE_EXITED_NEAR, 0, 0, 0);
+  for (std::set<View*>::const_iterator i = near_views_.begin();
+       i != near_views_.end(); ++i) {
+    if (near_views.find(*i) == near_views.end())
+      (*i)->OnMouseExitedNear(exited_near_event);
+  }
+
+  for (std::set<View*>::const_iterator i = near_views.begin();
+       i != near_views.end(); ++i) {
+    if (near_views_.find(*i) == near_views_.end()) {
+      MouseEvent entered_event(Event::ET_MOUSE_ENTERED,
+                               this,
+                               *i,
+                               e.location(),
+                               0);
+      (*i)->OnMouseNear(entered_event);
+    }
+  }
+
+  near_views_.swap(near_views);
 }
 
 void RootView::ProcessOnMouseExited() {
   if (mouse_move_handler_ != NULL) {
     MouseEvent exited_event(Event::ET_MOUSE_EXITED, 0, 0, 0);
     mouse_move_handler_->OnMouseExited(exited_event);
     mouse_move_handler_ = NULL;
   }
+
+  SendMouseExitedNear();
 }
 
 void RootView::SetMouseHandler(View *new_mh) {
   // If we're clearing the mouse handler, clear explicit_mouse_handler as well.
   explicit_mouse_handler_ = (new_mh != NULL);
   mouse_pressed_handler_ = new_mh;
 }
 
 void RootView::ProcessMouseDragCanceled() {
   if (mouse_pressed_handler_) {
@@ skipping 363 matching lines @@
   if (!view->registered_for_visible_bounds_notification_)
     return;
   view->registered_for_visible_bounds_notification_ = false;
   View* ancestor = view->GetParent();
   while (ancestor) {
     ancestor->RemoveDescendantToNotify(view);
     ancestor = ancestor->GetParent();
   }
 }
 
+void RootView::RegisterViewForNearNotification(View* view) {
+  registered_near_views_.insert(view);
+}
+
+void RootView::UnregisterViewForNearNotification(View* view) {
+  registered_near_views_.erase(view);
+  near_views_.erase(view);
+}
+
 void RootView::SetMouseLocationAndFlags(const MouseEvent& e) {
   last_mouse_event_flags_ = e.GetFlags();
   last_mouse_event_x_ = e.x();
   last_mouse_event_y_ = e.y();
 }
 
 std::string RootView::GetClassName() const {
   return kViewClassName;
 }
 
@@ skipping 36 matching lines @@
   gfx::NativeView native_view =
       static_cast<WidgetGtk*>(GetWidget())->window_contents();
   if (!native_view)
     return;
   gdk_window_set_cursor(native_view->window, cursor);
   if (cursor)
     gdk_cursor_destroy(cursor);
 #endif
 }
 
+void RootView::GetViewsRegisteredForNearNotification(
+    const MouseEvent& e,
+    std::set<View*>* near_views) {
+  const gfx::Point& location = e.location();
+  for (std::set<View*>::const_iterator i = registered_near_views_.begin();
+       i != registered_near_views_.end(); ++i) {
+    View* view = *i;
+    DCHECK(view->near_insets_.get());
+    const gfx::Insets& insets = *view->near_insets_;
+    gfx::Point view_loc(view->x() - insets.left(),
+                        view->y() - insets.top());
+    View::ConvertPointToView(view->GetParent(), this, &view_loc);
+    if (location.x() >= view_loc.x() &&
+        location.y() >= view_loc.y() &&
+        location.x() < view_loc.x() + (view->width() + insets.width()) &&
+        location.y() < view_loc.y() + (view->height() + insets.height())) {
+      near_views->insert(view);
+    }
+  }
+}
+
+void RootView::SendMouseExitedNear() {
+  if (near_views_.empty())
+    return;
+
+  MouseEvent exited_near_event(Event::ET_MOUSE_EXITED_NEAR, 0, 0, 0);
+  for (std::set<View*>::const_iterator i = near_views_.begin();
+       i != near_views_.end(); ++i) {
+    (*i)->OnMouseExitedNear(exited_near_event);
+  }
+
+  near_views_.clear();
+}
+
 }  // namespace views