Destroy GamepadDataFetchers on the polling thread.

device/gamepad/gamepad_provider.cc

 // 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.
 
 #include "device/gamepad/gamepad_provider.h"
 
 #include <stddef.h>
 #include <string.h>
 #include <cmath>
 #include <utility>
@@ skipping 54 matching lines @@
   Initialize(std::move(fetcher));
 }
 
 GamepadProvider::~GamepadProvider() {
   GamepadDataFetcherManager::GetInstance()->ClearProvider();
 
   base::SystemMonitor* monitor = base::SystemMonitor::Get();
   if (monitor)
     monitor->RemoveDevicesChangedObserver(this);
 
+  // Delete GamepadDataFetchers on |polling_thread_|. This is important because
+  // some of them require their destructor to be called on the same sequence as
+  // their other methods.
+  polling_thread_->task_runner()->PostTask(
+      FROM_HERE, base::Bind(&GamepadFetcherVector::clear,
+                            base::Unretained(&data_fetchers_)));
+
   // Use Stop() to join the polling thread, as there may be pending callbacks
   // which dereference |polling_thread_|.
   polling_thread_->Stop();
+
+  DCHECK(data_fetchers_.empty());
 }
 
 base::SharedMemoryHandle GamepadProvider::GetSharedMemoryHandleForProcess(
     base::ProcessHandle process) {
   base::SharedMemoryHandle renderer_handle;
   gamepad_shared_buffer_->shared_memory()->ShareToProcess(process,
                                                           &renderer_handle);
   return renderer_handle;
 }
 
@@ skipping 223 matching lines @@
     ever_had_user_gesture_ = true;
     for (size_t i = 0; i < user_gesture_observers_.size(); i++) {
       user_gesture_observers_[i].task_runner->PostTask(
           FROM_HERE, user_gesture_observers_[i].closure);
     }
     user_gesture_observers_.clear();
   }
 }
 
 }  // namespace device