Prevent multile DoPoll() calls from being simultaneously pending

content/browser/gamepad/gamepad_provider.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
 #define CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop_proxy.h"
@@ skipping 47 matching lines @@
 
   GamepadHardwareBuffer* SharedMemoryAsHardwareBuffer();
 
   enum { kDesiredSamplingIntervalMs = 16 };
 
   // Keeps track of when the background thread is paused. Access to is_paused_
   // must be guarded by is_paused_lock_.
   base::Lock is_paused_lock_;
   bool is_paused_;
 
+  // Keep track of when a polling task is schedlued, so as to prevent us from
+  // accidentally scheduling more than one at any time, when rapidly toggling
+  // |is_paused_|.
+  bool have_scheduled_do_poll_;
+
   // Updated based on notification from SystemMonitor when the system devices
   // have been updated, and this notification is passed on to the data fetcher
   // to enable it to avoid redundant (and possibly expensive) is-connected
   // tests. Access to devices_changed_ must be guarded by
   // devices_changed_lock_.
   base::Lock devices_changed_lock_;
   bool devices_changed_;
 
   // When polling_thread_ is running, members below are only to be used
   // from that thread.
   scoped_ptr<GamepadDataFetcher> data_fetcher_;
   base::SharedMemory gamepad_shared_memory_;
 
   // Polling is done on this background thread.
   scoped_ptr<base::Thread> polling_thread_;
 
   static GamepadProvider* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(GamepadProvider);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_