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

Index: chrome/browser/chromeos/file_manager/fake_disk_mount_manager.h
diff --git a/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.h b/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.h
index 14e3a887b3021c00bf85c55120d4214137780584..cef406d775920aa84679dc8e5f0fdfc6965180d9 100644
--- a/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.h
+++ b/chrome/browser/chromeos/file_manager/fake_disk_mount_manager.h
@@ -5,6 +5,7 @@
 #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>
 
@@ -51,6 +52,11 @@ class FakeDiskMountManager : public chromeos::disks::DiskMountManager {
     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;
@@ -66,6 +72,9 @@ class FakeDiskMountManager : public chromeos::disks::DiskMountManager {
                  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;
@@ -80,6 +89,7 @@ class FakeDiskMountManager : public chromeos::disks::DiskMountManager {
 
  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_;