Adding support to retrieve remaining and total space on disk/file shelf.

chrome/browser/chromeos/cros/mount_library.h

Index: chrome/browser/chromeos/cros/mount_library.h
diff --git a/chrome/browser/chromeos/cros/mount_library.h b/chrome/browser/chromeos/cros/mount_library.h
index 4f99389e12500a6d767ad97e5515d75f53c2b284..3f5129c216295da0015902fc4877140851df6ded 100644
--- a/chrome/browser/chromeos/cros/mount_library.h
+++ b/chrome/browser/chromeos/cros/mount_library.h
@@ -190,6 +190,11 @@ class MountLibrary {
   // |path| is device's mount path.
   virtual void UnmountPath(const char* path) = 0;
 
+  // Retrieves total and remaining available size on |mount_path|.
+  virtual void GetSizeStatsOnFileThread(const char* mount_path,
+                                        size_t* total_size_kb,
+                                        size_t* remaining_size_kb) = 0;
+
   // Formats device given its file path.
   // Example: file_path: /dev/sdb1
   virtual void FormatUnmountedDevice(const char* file_path) = 0;