Add a receiver interface to RemovableStorageNotifications.

chrome/browser/system_monitor/media_transfer_protocol_device_observer_linux.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 "chrome/browser/system_monitor/media_transfer_protocol_device_observer_linux.h"
 
 #include "base/file_path.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/string_split.h"
@@ skipping 167 matching lines @@
   StorageLocationToInfoMap::const_iterator info_it =
       storage_map_.find(GetDeviceLocationFromStorageName(path_components[1]));
   if (info_it == storage_map_.end())
     return false;
 
   if (storage_info)
     *storage_info = info_it->second;
   return true;
 }
 
+void MediaTransferProtocolDeviceObserverLinux::SetNotifications(
+    RemovableStorageNotifications::Receiver* notifications) {
+  notifications_ = notifications;
+}
+
 // device::MediaTransferProtocolManager::Observer override.
 void MediaTransferProtocolDeviceObserverLinux::StorageChanged(
     bool is_attached,
     const std::string& storage_name) {
   DCHECK(!storage_name.empty());
 
-  RemovableStorageNotifications* notifications =
-      RemovableStorageNotifications::GetInstance();
-  DCHECK(notifications);
-
   // New storage is attached.
   if (is_attached) {
     std::string device_id;
     string16 device_name;
     std::string location;
     get_storage_info_func_(storage_name, &device_id, &device_name, &location);
 
     // Keep track of device id and device name to see how often we receive
     // empty values.
     MediaStorageUtil::RecordDeviceInfoHistogram(false, device_id, device_name);
     if (device_id.empty() || device_name.empty())
       return;
 
     DCHECK(!ContainsKey(storage_map_, location));
 
     RemovableStorageNotifications::StorageInfo storage_info(
         device_id, device_name, location);
     storage_map_[location] = storage_info;
-    notifications->ProcessAttach(device_id, device_name, location);
+    if (notifications_)

[vandebo (ex-Chrome), 2013/01/31 23:51:29]

Why the condition?  Should always be true, right?  Passing in the constructor
would ensure that.

[Greg Billock, 2013/02/01 18:28:42]

Yes. This is defensive and mostly done for uniformity -- we do this elsewhere,
for testing reasons. I'll remove if you like, though. Agreed requiring it in the
constructor (everywhere) is the way to go.

[vandebo (ex-Chrome), 2013/02/01 18:59:55]

If everything works without it, then lets go that way so that we don't have to
remember to remove it once the receiver comes in through the constructor.

[Greg Billock, 2013/02/01 23:05:42]

Done.

+      notifications_->ProcessAttach(storage_info);
   } else {
     // Existing storage is detached.
     StorageLocationToInfoMap::iterator it =
         storage_map_.find(GetDeviceLocationFromStorageName(storage_name));
     if (it == storage_map_.end())
       return;
-    notifications->ProcessDetach(it->second.device_id);
+    if (notifications_)
+      notifications_->ProcessDetach(it->second.device_id);
     storage_map_.erase(it);
   }
 }
 
 void MediaTransferProtocolDeviceObserverLinux::EnumerateStorages() {
   typedef std::vector<std::string> StorageList;
   device::MediaTransferProtocolManager* mtp_manager =
       device::MediaTransferProtocolManager::GetInstance();
   StorageList storages = mtp_manager->GetStorages();
   for (StorageList::const_iterator storage_iter = storages.begin();
        storage_iter != storages.end(); ++storage_iter) {
     StorageChanged(true, *storage_iter);
   }
 }
 
 }  // namespace chrome