Make MountPointProvider pluggable from outside webkit/fileapi

webkit/fileapi/file_system_mount_point_provider.h

Index: webkit/fileapi/file_system_mount_point_provider.h
diff --git a/webkit/fileapi/file_system_mount_point_provider.h b/webkit/fileapi/file_system_mount_point_provider.h
index 9ca3997f73ed8e6091910a1b13028fd54979d2f4..98e7e8063842f50cccfdbbbd94a1969b7a6cbb87 100644
--- a/webkit/fileapi/file_system_mount_point_provider.h
+++ b/webkit/fileapi/file_system_mount_point_provider.h
@@ -43,6 +43,10 @@ class WEBKIT_STORAGE_EXPORT FileSystemMountPointProvider {
       DeleteFileSystemCallback;
   virtual ~FileSystemMountPointProvider() {}
 
+  // Returns true if this mount point provider can handle |type|.
+  // One mount point provider may be able to handle multiple filesystem types.
+  virtual bool CanHandleType(FileSystemType type) const = 0;
+
   // Validates the filesystem for the given |origin_url| and |type|.
   // This verifies if it is allowed to request (or create) the filesystem
   // and if it can access (or create) the root directory of the mount point.