[Mac] Show correct cursor after context menu is closed.

chrome/browser/tab_contents/tab_contents_view_mac.mm

Index: chrome/browser/tab_contents/tab_contents_view_mac.mm
===================================================================
--- chrome/browser/tab_contents/tab_contents_view_mac.mm	(revision 92355)
+++ chrome/browser/tab_contents/tab_contents_view_mac.mm	(working copy)
@@ -328,10 +328,10 @@
 }
 
 void TabContentsViewMac::ShowContextMenu(const ContextMenuParams& params) {
-  RenderViewContextMenuMac menu(tab_contents_,
-                                params,
-                                GetContentNativeView());
-  menu.Init();
+  context_menu_.reset(new RenderViewContextMenuMac(tab_contents(),
+                                                   params,
+                                                   GetContentNativeView()));
+  context_menu_->Init();
 }
 
 // Display a popup menu for WebKit using Cocoa widgets.