wm: Change the DispatcherClient interface.

ui/wm/public/dispatcher_client.h

Index: ui/wm/public/dispatcher_client.h
diff --git a/ui/wm/public/dispatcher_client.h b/ui/wm/public/dispatcher_client.h
index 9fd9c94326d8152841904020e682bde44200c3b2..d37a3a1909eddb386f4d4a6e0a38350f6301c315 100644
--- a/ui/wm/public/dispatcher_client.h
+++ b/ui/wm/public/dispatcher_client.h
@@ -5,6 +5,7 @@
 #ifndef UI_WM_PUBLIC_DISPATCHER_CLIENT_H_
 #define UI_WM_PUBLIC_DISPATCHER_CLIENT_H_
 
+#include "base/callback_forward.h"
 #include "base/message_loop/message_pump_dispatcher.h"
 #include "ui/aura/aura_export.h"
 
@@ -15,9 +16,8 @@ namespace client {
 // An interface implemented by an object which handles nested dispatchers.
 class AURA_EXPORT DispatcherClient {
  public:
-  virtual void RunWithDispatcher(base::MessagePumpDispatcher* dispatcher) = 0;
-
-  virtual void QuitNestedMessageLoop() = 0;
+  virtual void RunWithDispatcher(base::MessagePumpDispatcher* dispatcher,
+                                 base::Closure* quit_closure) = 0;

[sky, 2014/05/27 17:19:38]

It seems more natural to use a scoping object for this. Basically the same thing
as RunLoop. You create the RunLoop, run it, then destroy or quit it to cancel
the runloop. If you did that you could make RunWithDispatcher protected and
friend the RunLoop class.

[sadrul, 2014/05/27 17:37:14]

Do you mean something like:

  DispatcherClient* client = ...;
  DispatcherRunLoop run_loop = client->CreateNestedRunLoop();
  quit_closure_ = run_loop.QuitClosure();
  run_loop.Run();

?

 };
 
 AURA_EXPORT void SetDispatcherClient(Window* root_window,