MacViews: Clear mouse handler when showing context menus.

ui/views/controls/menu/menu_runner.cc

Index: ui/views/controls/menu/menu_runner.cc
diff --git a/ui/views/controls/menu/menu_runner.cc b/ui/views/controls/menu/menu_runner.cc
index bd07a839aefec3cd9f3e1492de5ff5ff2ebb904d..e3fe6d1b54dda839794e2e55e9f093855457c511 100644
--- a/ui/views/controls/menu/menu_runner.cc
+++ b/ui/views/controls/menu/menu_runner.cc
@@ -8,6 +8,7 @@
 
 #include "ui/views/controls/menu/menu_runner_handler.h"
 #include "ui/views/controls/menu/menu_runner_impl.h"
+#include "ui/views/widget/widget.h"
 
 namespace views {
 
@@ -56,6 +57,12 @@ MenuRunner::RunResult MenuRunner::RunMenuAt(Widget* parent,
     }
   }
 
+  // If we are shown on mouse press, we will eat the subsequent mouse down and
+  // the parent widget will not be able to reset its state (it might have mouse
+  // capture from the mouse down). So we clear its state here.
+  if (parent && parent->GetRootView())

[sky, 2016/10/26 17:46:11]

Can you clarify why you need need to move this here rather than in
MenuController? Also, please provide test coverage. 

[themblsha, 2016/10/27 15:05:28]

As tapted suggested in his first comment, this seems to be a common place among
ToolbarButton, Combobox and the MenuController. It seems that we can remove all
these hacks by fixing the problem in a common place they all use.

Also added the test.

+    parent->GetRootView()->SetMouseHandler(nullptr);
+
   return impl_->RunMenuAt(parent, button, bounds, anchor, run_types_);
 }