SystemMonitor: Pull device type into the device id

chrome/browser/media_gallery/media_storage_util.h

+// 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.
+
+// chrome::MediaStorageUtil provides information about storage devices attached
+// to the computer.
+
+#ifndef CHROME_BROWSER_MEDIA_GALLERY_MEDIA_STORAGE_UTIL_H_
+#define CHROME_BROWSER_MEDIA_GALLERY_MEDIA_STORAGE_UTIL_H_
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/file_path.h"
+
+namespace chrome {
+
+class MediaStorageUtil {
+ public:
+  enum Type {
+    // A USB mass storage device with a DCIM directory.
+    USB_MASS_STORAGE_WITH_DCIM,
+    // A USB mass storage device without a DCIM directory.
+    USB_MASS_STORAGE_NO_DCIM,
+    // Mass storage not connected through USB - a proxy for fixed/removable.
+    OTHER_MASS_STORAGE,
+    // A MTP or PTP device.
+    USB_MTP,
+  };
+
+  typedef base::Callback<void(bool)> BoolCallback;
+  typedef base::Callback<void(FilePath)> FilePathCallback;

[kmadhusu, 2012/08/20 17:13:50]

const FilePath&

[vandebo (ex-Chrome), 2012/08/20 18:35:14]

Both in this case the the one below, the purpose of the callback is so that work
can happen on a different thread.  This means that the caller (e.g. the stack
frame where the arguments live) will have gone out of scope by the time the
posted task is run.  Thus a const reference would be referencing an already
deleted object.  base/callback.h notes that you have to be careful of this
situation in the "PASSING PARAMETERS BY REFERENCE" section.

+  typedef base::Callback<void(std::string /*device id*/,

[kmadhusu, 2012/08/20 17:13:50]

const std::string&
const FilePath&

+                              FilePath /*path relative to device root*/,
+                              string16 /*display name*/)> DeviceInfoCallback;
+
+  // Returns a device id given properties of the device. A prefix dependent on
+  // |type| is added so |unique_id| need only be unique within the given type.
+  static std::string MakeDeviceId(Type type, const std::string& unique_id);
+
+  // Extracts the device |type| and |unique_id| from |device_id|.
+  static void CrackDeviceId(const std::string& device_id,
+                            Type* type, std::string* unique_id);
+
+  // Looks inside |device_id| to determine if it is a media device
+  // (type is USB_MASS_STORAGE_WITH_DCIM or USB_MTP).
+  static bool IsMediaDevice(const std::string& device_id);
+
+  // Looks inside |device_id| to determine if it is a media device
+  // (type isn't OTHER_MASS_STORAGE).
+  static bool IsRemovableDevice(const std::string& device_id);
+
+  // Determines if the device is attached to the computer.
+  static void IsDeviceAttached(const std::string& device_id,
+                               const BoolCallback& callback);
+
+  // Given |path|, get the device_id, relative path from the root of the
+  // device, and the device name.
+  static void GetDeviceInfoFromPath(const FilePath& path,
+                                    const DeviceInfoCallback& callback);
+
+  // Get a FilePath for the given |device_id|.  If the device isn't connected
+  // or isn't a mass storage type, the FilePath will be empty.
+  static void FindDevicePathById(const std::string& device_id,
+                                 const FilePathCallback& callback);
+
+ private:
+  // All methods are static, this class should not be instantiated.
+  MediaStorageUtil();
+
+  // A platform specific helper.
+  static void FindUSBDeviceById(const std::string unique_id,
+                                const FilePathCallback& callback);
+
+  DISALLOW_COPY_AND_ASSIGN(MediaStorageUtil);
+};
+
+}  // namespace chromeos

[kmadhusu, 2012/08/20 17:13:50]

chromeos => chrome

[vandebo (ex-Chrome), 2012/08/20 18:35:14]

Done.

+
+#endif  // CHROME_BROWSER_MEDIA_GALLERY_MEDIA_STORAGE_UTIL_H_