[Win, MediaGallery] Enumerate and handle mtp device attach/detach events.

chrome/browser/system_monitor/portable_device_watcher_win.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.
+//
+// Any tasks that communicates with the portable device may take >100ms to
+// complete. Those tasks should be run on an blocking thread instead of the
+// UI thread.
+
+#include "chrome/browser/system_monitor/portable_device_watcher_win.h"
+
+#include <dbt.h>
+#include <portabledevice.h>
+
+#include "base/file_path.h"
+#include "base/logging.h"
+#include "base/stl_util.h"
+#include "base/string_util.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "base/utf_string_conversions.h"
+#include "base/win/scoped_co_mem.h"
+#include "base/win/scoped_comptr.h"
+#include "chrome/browser/system_monitor/media_storage_util.h"
+#include "chrome/browser/system_monitor/removable_device_constants.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace chrome {
+
+namespace {
+
+// Name of the client application that communicates with the MTP device.
+const char16 kClientName[] = L"Chromium";
+
+// Name of the sequenced task runner.
+const char kMediaTaskRunnerName[] = "media-task-runner";
+
+// Returns true if |data| represents a class of portable devices.
+bool IsPortableDeviceStructure(LPARAM data) {
+  DEV_BROADCAST_HDR* broadcast_hdr =
+      reinterpret_cast<DEV_BROADCAST_HDR*>(data);
+  if (!broadcast_hdr ||
+      (broadcast_hdr->dbch_devicetype != DBT_DEVTYP_DEVICEINTERFACE)) {
+    return false;
+  }
+
+  GUID guidDevInterface = GUID_NULL;
+  if (FAILED(CLSIDFromString(kWPDDevInterfaceGUID, &guidDevInterface)))
+    return false;
+  DEV_BROADCAST_DEVICEINTERFACE* dev_interface =
+      reinterpret_cast<DEV_BROADCAST_DEVICEINTERFACE*>(data);
+  return (IsEqualGUID(dev_interface->dbcc_classguid, guidDevInterface) != 0);
+}
+
+// Returns the portable device plug and play device ID string.
+string16 GetPnpDeviceId(LPARAM data) {
+  DEV_BROADCAST_DEVICEINTERFACE* dev_interface =
+      reinterpret_cast<DEV_BROADCAST_DEVICEINTERFACE*>(data);
+  if (!dev_interface)
+    return string16();
+  string16 device_id(dev_interface->dbcc_name);
+  DCHECK(IsStringASCII(device_id));
+  return StringToLowerASCII(device_id);
+}
+
+// Gets the friendly name of the device specified by the |pnp_device_id|. On
+// success, returns true and fills in |name|.
+bool GetFriendlyName(const string16& pnp_device_id,
+                     IPortableDeviceManager* device_manager,
+                     string16* name) {
+  DCHECK(device_manager);
+  DCHECK(name);
+  DWORD name_len = 0;
+  HRESULT hr = device_manager->GetDeviceFriendlyName(pnp_device_id.c_str(),
+                                                     NULL, &name_len);
+  if (FAILED(hr))
+    return false;
+
+  hr = device_manager->GetDeviceFriendlyName(
+      pnp_device_id.c_str(), WriteInto(name, name_len), &name_len);
+  return (SUCCEEDED(hr) && !name->empty());
+}
+
+// Gets the manufacturer name of the device specified by the |pnp_device_id|.
+// On success, returns true and fills in |name|.
+bool GetManufacturerName(const string16& pnp_device_id,
+                         IPortableDeviceManager* device_manager,
+                         string16* name) {
+  DCHECK(device_manager);
+  DCHECK(name);
+  DWORD name_len = 0;
+  HRESULT hr = device_manager->GetDeviceManufacturer(pnp_device_id.c_str(),
+                                                     NULL, &name_len);
+  if (FAILED(hr))
+    return false;
+
+  hr = device_manager->GetDeviceManufacturer(pnp_device_id.c_str(),
+                                             WriteInto(name, name_len),
+                                             &name_len);
+  return (SUCCEEDED(hr) && !name->empty());
+}
+
+// Gets the description of the device specified by the |pnp_device_id|. On
+// success, returns true and fills in |description|.
+bool GetDeviceDescription(const string16& pnp_device_id,
+                          IPortableDeviceManager* device_manager,
+                          string16* description) {
+  DCHECK(device_manager);
+  DCHECK(description);
+  DWORD desc_len = 0;
+  HRESULT hr = device_manager->GetDeviceDescription(pnp_device_id.c_str(), NULL,
+                                                    &desc_len);
+  if (FAILED(hr))
+    return false;
+
+  hr = device_manager->GetDeviceDescription(pnp_device_id.c_str(),
+                                            WriteInto(description, desc_len),
+                                            &desc_len);
+  return (SUCCEEDED(hr) && !description->empty());
+}
+
+// On success, returns true and updates |client_info| with a reference to an
+// IPortableDeviceValues interface that holds information about the
+// application that communicates with the device.
+bool GetClientInformation(
+    base::win::ScopedComPtr<IPortableDeviceValues>* client_info) {
+  HRESULT hr = client_info->CreateInstance(__uuidof(PortableDeviceValues),
+                                           NULL, CLSCTX_INPROC_SERVER);
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to create an instance of IPortableDeviceValues";
+    return false;
+  }
+
+  // Attempt to set client details.
+  (*client_info)->SetStringValue(WPD_CLIENT_NAME, kClientName);
+  (*client_info)->SetUnsignedIntegerValue(WPD_CLIENT_MAJOR_VERSION, 0);
+  (*client_info)->SetUnsignedIntegerValue(WPD_CLIENT_MINOR_VERSION, 0);
+  (*client_info)->SetUnsignedIntegerValue(WPD_CLIENT_REVISION, 0);
+  (*client_info)->SetUnsignedIntegerValue(
+      WPD_CLIENT_SECURITY_QUALITY_OF_SERVICE, SECURITY_IMPERSONATION);
+  (*client_info)->SetUnsignedIntegerValue(WPD_CLIENT_DESIRED_ACCESS,
+                                          GENERIC_READ);
+  return true;
+}
+
+// Opens the device for communication. |pnp_device_id| specifies the plug and
+// play device ID string. On success, returns true and updates |device| with a
+// reference to the portable device interface.
+bool SetUp(const string16& pnp_device_id,
+           base::win::ScopedComPtr<IPortableDevice>* device) {
+  base::win::ScopedComPtr<IPortableDeviceValues> client_info;
+  if (!GetClientInformation(&client_info))
+    return false;
+
+  HRESULT hr = device->CreateInstance(__uuidof(PortableDevice), NULL,
+                                      CLSCTX_INPROC_SERVER);
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to create an instance of IPortableDevice";
+    return false;
+  }
+
+  hr = (*device)->Open(pnp_device_id.c_str(), client_info.get());
+  if (SUCCEEDED(hr))
+    return true;
+
+  if (hr == E_ACCESSDENIED)
+    DPLOG(ERROR) << "Access denied to open the device";
+  return false;
+}
+
+// Returns the unique id property key of the object specified by the
+// |object_id|.
+REFPROPERTYKEY GetUniqueIdPropertyKey(const string16& object_id) {
+  return (object_id == WPD_DEVICE_OBJECT_ID) ?
+      WPD_DEVICE_SERIAL_NUMBER : WPD_OBJECT_PERSISTENT_UNIQUE_ID;
+}
+
+// On success, returns true and populates |properties_to_read| with the
+// property key of the object specified by the |object_id|.
+bool PopulatePropertyKeyCollection(
+    const string16& object_id,
+    base::win::ScopedComPtr<IPortableDeviceKeyCollection>* properties_to_read) {
+  HRESULT hr = properties_to_read->CreateInstance(
+      __uuidof(PortableDeviceKeyCollection), NULL, CLSCTX_INPROC_SERVER);
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to create IPortableDeviceKeyCollection instance";
+    return false;
+  }
+  REFPROPERTYKEY key = GetUniqueIdPropertyKey(object_id);
+  hr = (*properties_to_read)->Add(key);
+  return SUCCEEDED(hr);
+}
+
+// Wrapper function to get content property string value.
+bool GetStringPropertyValue(IPortableDeviceValues* properties_values,
+                            REFPROPERTYKEY key,
+                            string16* value) {
+  DCHECK(properties_values);
+  DCHECK(value);
+  base::win::ScopedCoMem<char16> buffer;
+  HRESULT hr = properties_values->GetStringValue(key, &buffer);
+  if (FAILED(hr))
+    return false;
+  *value = static_cast<const char16*>(buffer);
+  return true;
+}
+
+// Constructs a unique identifier for the object specified by the |object_id|.
+// On success, returns true and fills in |unique_id|.
+bool GetObjectUniqueId(IPortableDevice* device,
+                       const string16& object_id,
+                       string16* unique_id) {
+  DCHECK(device);
+  DCHECK(unique_id);
+  base::win::ScopedComPtr<IPortableDeviceContent> content;
+  HRESULT hr = device->Content(content.Receive());
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to get IPortableDeviceContent interface";
+    return false;
+  }
+
+  base::win::ScopedComPtr<IPortableDeviceProperties> properties;
+  hr = content->Properties(properties.Receive());
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to get IPortableDeviceProperties interface";
+    return false;
+  }
+
+  base::win::ScopedComPtr<IPortableDeviceKeyCollection> properties_to_read;
+  if (!PopulatePropertyKeyCollection(object_id, &properties_to_read))
+    return false;
+
+  base::win::ScopedComPtr<IPortableDeviceValues> properties_values;
+  if (FAILED(properties->GetValues(object_id.c_str(),
+                                   properties_to_read.get(),
+                                   properties_values.Receive()))) {
+    return false;
+  }
+
+  REFPROPERTYKEY key = GetUniqueIdPropertyKey(object_id);
+  return GetStringPropertyValue(properties_values.get(), key, unique_id);
+}
+
+// Constructs the device storage unique identifier using |device_serial_num| and
+// |storage_id|. On success, returns true and fills in |device_storage_id|.
+bool ConstructDeviceStorageUniqueId(const string16& device_serial_num,
+                                    const string16& storage_id,
+                                    std::string* device_storage_id) {
+  if (device_serial_num.empty() && storage_id.empty())
+    return false;
+
+  DCHECK(device_storage_id);
+  *device_storage_id = MediaStorageUtil::MakeDeviceId(
+       MediaStorageUtil::MTP_OR_PTP,
+       UTF16ToUTF8(storage_id + L':' + device_serial_num));
+  return true;
+}
+
+// Gets a list of removable storage object identifiers present in |device|.
+// On success, returns true and fills in |storage_object_ids|.
+bool GetRemovableStorageObjectIds(
+    IPortableDevice* device,
+    PortableDeviceWatcherWin::StorageObjectIDs* storage_object_ids) {
+  DCHECK(device);
+  DCHECK(storage_object_ids);
+  base::win::ScopedComPtr<IPortableDeviceCapabilities> capabilities;
+  HRESULT hr = device->Capabilities(capabilities.Receive());
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to get IPortableDeviceCapabilities interface";
+    return false;
+  }
+
+  base::win::ScopedComPtr<IPortableDevicePropVariantCollection> storage_ids;
+  hr = capabilities->GetFunctionalObjects(WPD_FUNCTIONAL_CATEGORY_STORAGE,
+                                          storage_ids.Receive());
+  if (FAILED(hr)) {
+    DPLOG(ERROR) << "Failed to get IPortableDevicePropVariantCollection";
+    return false;
+  }
+
+  DWORD num_storage_obj_ids = 0;
+  hr = storage_ids->GetCount(&num_storage_obj_ids);
+  if (FAILED(hr))
+    return false;
+
+  for (DWORD index = 0; index < num_storage_obj_ids; ++index) {
+    PROPVARIANT object_id = {0};
+    PropVariantInit(&object_id);
+    hr = storage_ids->GetAt(index, &object_id);
+    if (SUCCEEDED(hr) && (object_id.pwszVal != NULL) &&
+        (object_id.vt == VT_LPWSTR)) {
+      storage_object_ids->push_back(object_id.pwszVal);
+    }
+    PropVariantClear(&object_id);
+  }
+  return true;
+}
+
+// Returns true if the portable device is mounted on a volume. |device_name|
+// specifies the name of the device.
+bool IsVolumeMountedPortableDevice(const string16& device_name) {
+  // If the device is a volume mounted device, |device_name| will be
+  // the volume name.
+  return ((device_name.length() >= 2) && (device_name[1] == L':') &&
+      (((device_name[0] >= L'A') && (device_name[0] <= L'Z')) ||
+          ((device_name[0] >= L'a') && (device_name[0] <= L'z'))));
+}
+
+// Returns the name of the device specified by |pnp_device_id|.
+string16 GetDeviceNameOnBlockingThread(
+    IPortableDeviceManager* portable_device_manager,
+    const string16& pnp_device_id) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  DCHECK(portable_device_manager);
+  string16 name;
+  GetFriendlyName(pnp_device_id, portable_device_manager, &name) ||
+      GetDeviceDescription(pnp_device_id, portable_device_manager, &name) ||
+      GetManufacturerName(pnp_device_id, portable_device_manager, &name);
+  return name;
+}
+
+// Access the device and gets the device storage details. On success, returns
+// true and populates |storage_objects| with device storage details.
+bool GetDeviceStorageObjectsOnBlockingThread(
+    const string16& pnp_device_id,
+    PortableDeviceWatcherWin::StorageObjects* storage_objects) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  DCHECK(storage_objects);
+  base::win::ScopedComPtr<IPortableDevice> device;
+  if (!SetUp(pnp_device_id, &device))
+    return false;
+
+  string16 device_serial_num;
+  if (!GetObjectUniqueId(device.get(), WPD_DEVICE_OBJECT_ID,
+                         &device_serial_num)) {
+    return false;
+  }
+
+  PortableDeviceWatcherWin::StorageObjectIDs storage_obj_ids;
+  if (!GetRemovableStorageObjectIds(device.get(), &storage_obj_ids))
+    return false;
+  for (PortableDeviceWatcherWin::StorageObjectIDs::const_iterator id_iter =
+       storage_obj_ids.begin(); id_iter != storage_obj_ids.end(); ++id_iter) {
+    string16 storage_persistent_id;
+    if (!GetObjectUniqueId(device.get(), *id_iter, &storage_persistent_id))
+      continue;
+
+    std::string device_storage_id;
+    if (ConstructDeviceStorageUniqueId(device_serial_num, storage_persistent_id,
+                                       &device_storage_id)) {
+      storage_objects->push_back(PortableDeviceWatcherWin::DeviceStorageObject(
+          *id_iter, device_storage_id));
+    }
+  }
+  return true;
+}
+
+// Accesses the device and gets the device details (name, storage info, etc).
+// On success returns true and fills in |device_details|. On failure, returns
+// false. |pnp_device_id| specifies the plug and play device ID string.
+bool GetDeviceInfoOnBlockingThread(
+    IPortableDeviceManager* portable_device_manager,
+    const string16& pnp_device_id,
+    PortableDeviceWatcherWin::DeviceDetails* device_details) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  DCHECK(portable_device_manager);
+  DCHECK(device_details);
+  DCHECK(!pnp_device_id.empty());
+  device_details->name = GetDeviceNameOnBlockingThread(portable_device_manager,
+                                                       pnp_device_id);
+  if (IsVolumeMountedPortableDevice(device_details->name))
+    return false;
+
+  device_details->location = pnp_device_id;
+  PortableDeviceWatcherWin::StorageObjects storage_objects;
+  return GetDeviceStorageObjectsOnBlockingThread(
+      pnp_device_id, &device_details->storage_objects);
+}
+
+// Wrapper function to get an instance of portable device manager. On success,
+// returns true and fills in |portable_device_mgr|. On failure, returns false.
+bool GetPortableDeviceManager(
+  base::win::ScopedComPtr<IPortableDeviceManager>* portable_device_mgr) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  HRESULT hr = portable_device_mgr->CreateInstance(
+      __uuidof(PortableDeviceManager), NULL, CLSCTX_INPROC_SERVER);
+  if (SUCCEEDED(hr))
+    return true;
+
+  // Either there is no portable device support (Windows XP with old versions of
+  // Media Player) or the thread does not have COM initialized.
+  DCHECK_NE(CO_E_NOTINITIALIZED, hr);
+  return false;
+}
+
+// Enumerates the attached portable devices. On success, returns true and fills
+// in |devices| with the attached portable device details. On failure, returns
+// false.
+bool EnumerateAttachedDevicesOnBlockingThread(
+    PortableDeviceWatcherWin::Devices* devices) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  DCHECK(devices);
+  base::win::ScopedComPtr<IPortableDeviceManager> portable_device_mgr;
+  if (!GetPortableDeviceManager(&portable_device_mgr))
+    return false;
+
+  // Get the total number of devices found on the system.
+  DWORD pnp_device_count = 0;
+  HRESULT hr = portable_device_mgr->GetDevices(NULL, &pnp_device_count);
+  if (FAILED(hr))
+    return false;
+
+  scoped_array<char16*> pnp_device_ids(new char16*[pnp_device_count]);
+  ZeroMemory(pnp_device_ids.get(), pnp_device_count);
+  hr = portable_device_mgr->GetDevices(pnp_device_ids.get(), &pnp_device_count);
+  if (FAILED(hr))
+    return false;
+
+  for (DWORD index = 0; index < pnp_device_count; ++index) {
+    PortableDeviceWatcherWin::DeviceDetails device_details;
+    if (GetDeviceInfoOnBlockingThread(
+        portable_device_mgr, pnp_device_ids[index], &device_details))
+      devices->push_back(device_details);
+  }
+  return !devices->empty();
+}
+
+// Handles the device attach event message on a media task runner.
+// |pnp_device_id| specifies the attached plug and play device ID string. On
+// success, returns true and populates |device_details| with device information.
+// On failure, returns false.
+bool HandleDeviceAttachedEventOnBlockingThread(
+    const string16& pnp_device_id,
+    PortableDeviceWatcherWin::DeviceDetails* device_details) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+  DCHECK(device_details);
+  base::win::ScopedComPtr<IPortableDeviceManager> portable_device_mgr;
+  if (!GetPortableDeviceManager(&portable_device_mgr))
+    return false;
+  // Sometimes, portable device manager doesn't have the new device details.
+  // Refresh the manager device list to update its details.
+  portable_device_mgr->RefreshDeviceList();
+  return GetDeviceInfoOnBlockingThread(portable_device_mgr, pnp_device_id,
+                                       device_details);
+}
+
+// Constructs and returns a storage path from storage unique identifier.
+string16 GetStoragePathFromStorageId(const std::string& storage_unique_id) {
+  // Construct a dummy device path using the storage name. This is only used
+  // for registering the device media file system.
+  DCHECK(!storage_unique_id.empty());
+  return UTF8ToUTF16("\\\\" + storage_unique_id);
+}
+
+// Registers |hwnd| to receive portable device notification details. On success,
+// returns the device notifications handle else returns NULL.
+HDEVNOTIFY RegisterPortableDeviceNotification(HWND hwnd) {
+  GUID dev_interface_guid = GUID_NULL;
+  HRESULT hr = CLSIDFromString(kWPDDevInterfaceGUID, &dev_interface_guid);
+  if (FAILED(hr))
+    return NULL;
+  DEV_BROADCAST_DEVICEINTERFACE db = {
+      sizeof(DEV_BROADCAST_DEVICEINTERFACE),
+      DBT_DEVTYP_DEVICEINTERFACE,
+      0,
+      dev_interface_guid
+  };
+  return RegisterDeviceNotification(hwnd, &db, DEVICE_NOTIFY_WINDOW_HANDLE);
+}
+
+}  // namespace
+
+
+// PortableDeviceWatcherWin ---------------------------------------------------
+
+PortableDeviceWatcherWin::DeviceStorageObject::DeviceStorageObject(
+    const string16& temporary_id,
+    const std::string& persistent_id)
+    : object_temporary_id(temporary_id),
+      object_persistent_id(persistent_id) {
+}
+
+PortableDeviceWatcherWin::PortableDeviceWatcherWin()
+    : notifications_(NULL),
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
+}
+
+PortableDeviceWatcherWin::~PortableDeviceWatcherWin() {
+  UnregisterDeviceNotification(notifications_);
+}
+
+void PortableDeviceWatcherWin::Init(HWND hwnd) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  notifications_ = RegisterPortableDeviceNotification(hwnd);
+  base::SequencedWorkerPool* pool = content::BrowserThread::GetBlockingPool();
+  media_task_runner_ = pool->GetSequencedTaskRunnerWithShutdownBehavior(
+      pool->GetNamedSequenceToken(kMediaTaskRunnerName),
+      base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
+  EnumerateAttachedDevices();
+}
+
+void PortableDeviceWatcherWin::OnWindowMessage(UINT event_type, LPARAM data) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  if (!IsPortableDeviceStructure(data))
+    return;
+
+  string16 device_id = GetPnpDeviceId(data);
+  if (event_type == DBT_DEVICEARRIVAL)
+    HandleDeviceAttachEvent(device_id);
+  else if (event_type == DBT_DEVICEREMOVECOMPLETE)
+    HandleDeviceDetachEvent(device_id);
+}
+
+void PortableDeviceWatcherWin::EnumerateAttachedDevices() {
+  DCHECK(media_task_runner_.get());
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  Devices* devices = new Devices;
+  base::PostTaskAndReplyWithResult(
+      media_task_runner_,
+      FROM_HERE,
+      base::Bind(&EnumerateAttachedDevicesOnBlockingThread, devices),
+      base::Bind(&PortableDeviceWatcherWin::OnDidEnumerateAttachedDevices,
+                 weak_ptr_factory_.GetWeakPtr(), base::Owned(devices)));
+}
+
+void PortableDeviceWatcherWin::OnDidEnumerateAttachedDevices(
+    const Devices* devices, const bool result) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  DCHECK(devices);
+  if (!result)
+    return;
+  for (Devices::const_iterator device_iter = devices->begin();
+       device_iter != devices->end(); ++device_iter) {
+    OnDidHandleDeviceAttachEvent(&(*device_iter), result);
+  }
+}
+
+void PortableDeviceWatcherWin::HandleDeviceAttachEvent(
+    const string16& pnp_device_id) {
+  DCHECK(media_task_runner_.get());
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  DeviceDetails* device_details = new DeviceDetails;
+  base::PostTaskAndReplyWithResult(
+      media_task_runner_,
+      FROM_HERE,
+      base::Bind(&HandleDeviceAttachedEventOnBlockingThread, pnp_device_id,
+                 device_details),
+      base::Bind(&PortableDeviceWatcherWin::OnDidHandleDeviceAttachEvent,
+                 weak_ptr_factory_.GetWeakPtr(), base::Owned(device_details)));
+}
+
+void PortableDeviceWatcherWin::OnDidHandleDeviceAttachEvent(
+    const DeviceDetails* device_details, const bool result) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  DCHECK(device_details);
+  if (!result)
+    return;
+
+  const StorageObjects& storage_objects = device_details->storage_objects;
+  const string16& name = device_details->name;
+  const string16& location = device_details->location;
+  DCHECK(!ContainsKey(device_map_, location));
+  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+  DCHECK(system_monitor);
+  for (StorageObjects::const_iterator storage_iter = storage_objects.begin();
+       storage_iter != storage_objects.end(); ++storage_iter) {
+    const std::string& storage_id = storage_iter->object_persistent_id;
+    DCHECK(!ContainsKey(storage_map_, storage_id));
+
+    // Keep track of storage id and storage name to see how often we receive
+    // empty values.
+    MediaStorageUtil::RecordDeviceInfoHistogram(false, storage_id, name);
+    if (storage_id.empty() || name.empty())
+      return;
+
+    // Device can have several data partitions. Therefore, add the
+    // partition identifier to the storage name. E.g.: "Nexus 7 (s10001)"
+    string16 storage_name(name + L" (" + storage_iter->object_temporary_id +
+        L')');
+    storage_map_[storage_id] =
+        base::SystemMonitor::RemovableStorageInfo(storage_id, storage_name,
+                                                  location);
+    system_monitor->ProcessRemovableStorageAttached(
+        storage_id, storage_name, GetStoragePathFromStorageId(storage_id));
+  }
+  device_map_[location] = storage_objects;
+}
+
+void PortableDeviceWatcherWin::HandleDeviceDetachEvent(
+    const string16& pnp_device_id) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  MTPDeviceMap::iterator device_iter = device_map_.find(pnp_device_id);
+  if (device_iter == device_map_.end())
+    return;
+
+  base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
+  DCHECK(system_monitor);
+
+  const StorageObjects& storage_objects = device_iter->second;
+  for (StorageObjects::const_iterator storage_object_iter =
+       storage_objects.begin(); storage_object_iter != storage_objects.end();
+       ++storage_object_iter) {
+    std::string storage_id = storage_object_iter->object_persistent_id;
+    MTPStorageMap::iterator storage_iter = storage_map_.find(storage_id);

[Peter Kasting, 2012/10/30 23:58:32]

Nit: Might want to name this |storage_map_iter| to reduce confusion

[kmadhusu, 2012/10/31 00:16:22]

Done.

+    DCHECK(storage_iter != storage_map_.end());
+    system_monitor->ProcessRemovableStorageDetached(
+        storage_iter->second.device_id);
+    storage_map_.erase(storage_iter);
+  }
+  device_map_.erase(device_iter);
+}
+
+}  // namespace chrome