linux: fix main loop issues with windowless plugins

base/message_pump_glib.h

 // Copyright (c) 2008 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 BASE_MESSAGE_PUMP_GLIB_H_
 #define BASE_MESSAGE_PUMP_GLIB_H_
 
 #include <gtk/gtk.h>
 #include <glib.h>
 
@@ skipping 24 matching lines @@
   ~MessagePumpForUI();
 
   virtual void Run(Delegate* delegate);
   virtual void Quit();
   virtual void ScheduleWork();
   virtual void ScheduleDelayedWork(const Time& delayed_work_time);
 
   // Internal methods used for processing the pump callbacks.  They are
   // public for simplicity but should not be used directly.  HandlePrepare
   // is called during the prepare step of glib, and returns a timeout that
-  // will be passed to the poll.  HandleDispatch is called after the poll
-  // has completed.
+  // will be passed to the poll. HandleCheck is called after the poll
+  // has completed, and returns whether or not HandleDispatch should be called.
+  // HandleDispatch is called if HandleCheck returned true.
   int HandlePrepare();
+  bool HandleCheck();
   void HandleDispatch();
 
   // Add an Observer, which will start receiving notifications immediately.
   void AddObserver(Observer* observer);
 
   // Remove an Observer.  It is safe to call this method while an Observer is
   // receiving a notification callback.
   void RemoveObserver(Observer* observer);
 
  private:
   // We may make recursive calls to Run, so we save state that needs to be
   // separate between them in this structure type.
   struct RunState {
     Delegate* delegate;
 
     // Used to flag that the current Run() invocation should return ASAP.
     bool should_quit;
 
     // Used to count how many Run() invocations are on the stack.
     int run_depth;
 
-    // Used internally for controlling whether we want a message pump
-    // iteration to be blocking or not.
-    bool more_work_is_plausible;
+    // This keeps the state of whether the pump got signaled that there was new
+    // work to be done. Since we eat the message on the wake up pipe as soon as
+    // we get it, we keep that state here to stay consistent.
+    bool has_work;
   };
 
   // Invoked from EventDispatcher. Notifies all observers we're about to
   // process an event.
   void WillProcessEvent(GdkEvent* event);
 
   // Invoked from EventDispatcher. Notifies all observers we processed an
   // event.
   void DidProcessEvent(GdkEvent* event);
 
@@ skipping 24 matching lines @@
 
   // List of observers.
   ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI);
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_PUMP_GLIB_H_