Fix a bug that unmounting devices on the policy update can be a busy loop.

chrome/browser/chromeos/file_manager/fake_disk_mount_manager.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 CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FAKE_DISK_MOUNT_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FAKE_DISK_MOUNT_MANAGER_H_
 
+#include <queue>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chromeos/dbus/cros_disks_client.h"
 #include "chromeos/disks/disk_mount_manager.h"
 
 namespace file_manager {
@@ skipping 26 matching lines @@
   FakeDiskMountManager();
   ~FakeDiskMountManager() override;
 
   const std::vector<MountRequest>& mount_requests() const {
     return mount_requests_;
   }
   const std::vector<UnmountRequest>& unmount_requests() const {
     return unmount_requests_;
   }
 
+  // Emulates that all mount request finished.
+  // Return true if there was one or more mount request enqueued, or false
+  // otherwise.
+  bool FinishAllUnmountPathRequests();
+
   // DiskMountManager overrides.
   void AddObserver(Observer* observer) override;
   void RemoveObserver(Observer* observer) override;
   const DiskMap& disks() const override;
   const Disk* FindDiskBySourcePath(
       const std::string& source_path) const override;
   const MountPointMap& mount_points() const override;
   void EnsureMountInfoRefreshed(
       const EnsureMountInfoRefreshedCallback& callback,
       bool force) override;
   void MountPath(const std::string& source_path,
                  const std::string& source_format,
                  const std::string& mount_label,
                  chromeos::MountType type,
                  chromeos::MountAccessMode access_mode) override;
+  // In order to simulate asynchronous invocation of callbacks after unmount
+  // is finished, |callback| will be invoked only when
+  // |FinishAllUnmountRequest()| is called.
   void UnmountPath(const std::string& mount_path,
                    chromeos::UnmountOptions options,
                    const UnmountPathCallback& callback) override;
   void FormatMountedDevice(const std::string& mount_path) override;
   void UnmountDeviceRecursively(
       const std::string& device_path,
       const UnmountDeviceRecursivelyCallbackType& callback) override;
 
   bool AddDiskForTest(std::unique_ptr<Disk> disk) override;
   bool AddMountPointForTest(const MountPointInfo& mount_point) override;
   void InvokeDiskEventForTest(DiskEvent event, const Disk* disk);
 
  private:
   base::ObserverList<Observer> observers_;
+  std::queue<UnmountPathCallback> pending_unmount_callbacks_;

[Lei Zhang, 2016/09/27 17:21:02]

With this, we can no longer depend on base/callback_forward.h, and we have to
include base/callback.h.

https://codereview.chromium.org/2376733002

 
   DiskMap disks_;
   MountPointMap mount_points_;
 
   std::vector<MountRequest> mount_requests_;
   std::vector<UnmountRequest> unmount_requests_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeDiskMountManager);
 };
 
 }  // namespace file_manager
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_MANAGER_FAKE_DISK_MOUNT_MANAGER_H_