This is UI side unreadable device support.

chrome/browser/chromeos/cros/mount_library.h

 // Copyright (c) 2011 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_CROS_MOUNT_LIBRARY_H_
 #define CHROME_BROWSER_CHROMEOS_CROS_MOUNT_LIBRARY_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 11 matching lines @@
   MOUNT_DISK_CHANGED,
   MOUNT_DISK_MOUNTED,
   MOUNT_DISK_UNMOUNTED,
   MOUNT_DEVICE_ADDED,
   MOUNT_DEVICE_REMOVED,
   MOUNT_DEVICE_SCANNED,
   MOUNT_FORMATTING_STARTED,
   MOUNT_FORMATTING_FINISHED
 } MountLibraryEventType;
 
+typedef enum MountCondition {
+  MOUNT_CONDITION_NONE,
+  MOUNT_CONDITION_UNKNOWN_FILESYSTEM,
+  MOUNT_CONDITION_UNSUPPORTED_FILESYSTEM
+} MountCondition;
+
 class MountLibcrosProxy {
  public:
   virtual ~MountLibcrosProxy() {}
   virtual void CallMountPath(const char* source_path,
                              MountType type,
                              const MountPathOptions& options,
                              MountCompletedMonitor callback,
                              void* object) = 0;
   virtual void CallUnmountPath(const char* path,
                                UnmountRequestCallback callback,
@@ skipping 86 matching lines @@
     bool has_media_;
     bool on_boot_device_;
   };
   typedef std::map<std::string, Disk*> DiskMap;
   typedef std::map<std::string, std::string> PathMap;
 
   struct MountPointInfo {
     std::string source_path;
     std::string mount_path;
     MountType mount_type;
+    MountCondition mount_condition;

[tbarzic, 2011/08/25 02:03:44]

hm.. better than special_data :)
I would still consider making its name specific for data it holds a the moment
(if we decide to add some more meaning it shouldn't be a problem to change its
name)...
but I'm ok with what ever you decide..

[sidor, 2011/08/25 18:02:13]

Ok, I agree, but hmm... It's really hard to invent and a name that will be
specific but also not overdescriptive. We don't want
IsDeviceMountedEvenThoughFilesystemWasNotRecognised :D So I will leave it as
mountConditions. It shouldn't be too confusing because if somebody don't know
what it is, it's really easy to look up enum and see the possible values. 

[tbarzic, 2011/08/25 18:17:54]

Yeah, actually, when I think about it..this is quite good name ;) 

 
-    MountPointInfo(const char* source, const char* mount, const MountType type)
+    MountPointInfo(const char* source, const char* mount, const MountType type,
+        MountCondition condition)
         : source_path(source ? source : ""),
           mount_path(mount ? mount : ""),
-          mount_type(type) {
+          mount_type(type),
+          mount_condition(condition) {
     }
   };
 
   // MountPointMap key is mount_path.
   typedef std::map<std::string, MountPointInfo> MountPointMap;
 
   typedef void(*UnmountDeviceRecursiveCallbackType)(void*, bool);
 
   class Observer {
    public:
     virtual ~Observer() {}
     // Async API events.
     virtual void DiskChanged(MountLibraryEventType event,
                              const Disk* disk) = 0;
     virtual void DeviceChanged(MountLibraryEventType event,
-                               const std::string& device_path ) = 0;
+                               const std::string& device_path) = 0;
     virtual void MountCompleted(MountEvent event_type,
                                 MountError error_code,
                                 const MountPointInfo& mount_info) = 0;
   };
 
   virtual ~MountLibrary() {}
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
   virtual const DiskMap& disks() const = 0;
   virtual const MountPointMap& mount_points() const = 0;
@@ skipping 13 matching lines @@
   // Example: mount_path: /media/VOLUME_LABEL
   virtual void FormatMountedDevice(const char* mount_path) = 0;
 
   // Unmounts device_poath and all of its known children.
   virtual void UnmountDeviceRecursive(const char* device_path,
       UnmountDeviceRecursiveCallbackType callback, void* user_data) = 0;
 
   // Helper functions for parameter conversions.
   static std::string MountTypeToString(MountType type);
   static MountType MountTypeFromString(const std::string& type_str);
+  static std::string MountConditionToString(MountCondition type);
 
   // Used in testing. Enables mocking libcros.
   virtual void SetLibcrosProxy(MountLibcrosProxy* proxy) {}
 
   // Factory function, creates a new instance and returns ownership.
   // For normal usage, access the singleton via CrosLibrary::Get().
   static MountLibrary* GetImpl(bool stub);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROS_MOUNT_LIBRARY_H_