Add the ability to observe MessagePumpMojo

mojo/common/message_pump_mojo.h

 // Copyright 2013 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.
 
 #ifndef MOJO_COMMON_MESSAGE_PUMP_MOJO_H_
 #define MOJO_COMMON_MESSAGE_PUMP_MOJO_H_
 
 #include <map>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_pump.h"
+#include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "mojo/common/mojo_common_export.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 namespace common {
 
 class MessagePumpMojoHandler;
 
 // Mojo implementation of MessagePump.
 class MOJO_COMMON_EXPORT MessagePumpMojo : public base::MessagePump {
  public:
+  class Observer {
+   public:
+    Observer() {}
+
+    virtual void WillSignalHandler() = 0;
+    virtual void DidSignalHandler() = 0;
+
+   protected:
+    virtual ~Observer() {}
+  };
+
   MessagePumpMojo();
   virtual ~MessagePumpMojo();
 
   // Static factory function (for using with |base::Thread::Options|, wrapped
   // using |base::Bind()|).
   static scoped_ptr<base::MessagePump> Create();
 
   // Returns the MessagePumpMojo instance of the current thread, if it exists.
   static MessagePumpMojo* current();
 
   static bool IsCurrent() { return !!current(); }
 
   // Registers a MessagePumpMojoHandler for the specified handle. Only one
   // handler can be registered for a specified handle.
   // NOTE: a value of 0 for |deadline| indicates an indefinite timeout.
   void AddHandler(MessagePumpMojoHandler* handler,
                   const Handle& handle,
                   MojoHandleSignals wait_signals,
                   base::TimeTicks deadline);
 
   void RemoveHandler(const Handle& handle);
 
+  void AddObserver(Observer*);
+  void RemoveObserver(Observer*);
+
   // MessagePump:
   virtual void Run(Delegate* delegate) override;
   virtual void Quit() override;
   virtual void ScheduleWork() override;
   virtual void ScheduleDelayedWork(
       const base::TimeTicks& delayed_work_time) override;
 
  private:
   struct RunState;
   struct WaitState;
@@ skipping 23 matching lines @@
   // invalid handle.
   void RemoveFirstInvalidHandle(const WaitState& wait_state);
 
   void SignalControlPipe(const RunState& run_state);
 
   WaitState GetWaitState(const RunState& run_state) const;
 
   // Returns the deadline for the call to MojoWaitMany().
   MojoDeadline GetDeadlineForWait(const RunState& run_state) const;
 
+  void WillSignalHandler();
+  void DidSignalHandler();
+
   // If non-NULL we're running (inside Run()). Member is reference to value on
   // stack.
   RunState* run_state_;
 
   // Lock for accessing |run_state_|. In general the only method that we have to
   // worry about is ScheduleWork(). All other methods are invoked on the same
   // thread.
   base::Lock run_state_lock_;
 
   HandleToHandler handlers_;
 
   // An ever increasing value assigned to each Handler::id. Used to detect
   // uniqueness while notifying. That is, while notifying expired timers we copy
   // |handlers_| and only notify handlers whose id match. If the id does not
   // match it means the handler was removed then added so that we shouldn't
   // notify it.
   int next_handler_id_;
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(MessagePumpMojo);
 };
 
 }  // namespace common
 }  // namespace mojo
 
 #endif  // MOJO_COMMON_MESSAGE_PUMP_MOJO_H_