While changing the label class I added a DCHECK to make sure the function...

views/controls/label.cc

 // Copyright (c) 2009 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/controls/label.h"
 
 #include <math.h>
 #include <limits>
 
 #include "app/gfx/canvas.h"
@@ skipping 400 matching lines @@
   }
   return insets;
 }
 
 // static
 gfx::Font Label::GetDefaultFont() {
   return ResourceBundle::GetSharedInstance().GetFont(ResourceBundle::BaseFont);
 }
 
 void Label::UpdateContainsMouse(const MouseEvent& event) {
-  SetContainsMouse(GetTextBounds().Contains(event.x(), event.y()));
+  if (is_multi_line_) {
+    gfx::Rect rect(width(), GetHeightForWidth(width()));
+    SetContainsMouse(rect.Contains(event.x(), event.y()));
+  } else {
+    SetContainsMouse(GetTextBounds().Contains(event.x(), event.y()));
+  }
 }
 
 void Label::SetContainsMouse(bool contains_mouse) {
   if (contains_mouse_ == contains_mouse)
     return;
   contains_mouse_ = contains_mouse;
   if (GetMouseOverBackground())
     SchedulePaint();
 }
 
@@ skipping 62 matching lines @@
 }
 
 bool Label::GetAccessibleState(AccessibilityTypes::State* state) {
   DCHECK(state);
 
   *state = AccessibilityTypes::STATE_READONLY;
   return true;
 }
 
 }  // namespace views