Add RevokeFileSystem back to IsolatedContext

webkit/fileapi/isolated_context.h

Index: webkit/fileapi/isolated_context.h
diff --git a/webkit/fileapi/isolated_context.h b/webkit/fileapi/isolated_context.h
index 5593c629877c56226a9b214e50dfe70085f8c051..3888dfecd3ab5ae3462e35fffa20ba3c12f985e6 100644
--- a/webkit/fileapi/isolated_context.h
+++ b/webkit/fileapi/isolated_context.h
@@ -101,6 +101,10 @@ class FILEAPI_EXPORT IsolatedContext {
                                         const FilePath& path,
                                         std::string* register_name);
 
+  // Revokes the filesystem |filesystem_id|
+  // Returns false if the |filesystem_id| is not (no longer) registered.
+  bool RevokeFileSystem(const std::string& filesystem_id);
+
   // Revokes all filesystem(s) registered for the given path.
   // This is assumed to be called when the registered path becomes
   // globally invalid, e.g. when a device for the path is detached.
@@ -209,6 +213,10 @@ class FILEAPI_EXPORT IsolatedContext {
   IsolatedContext();
   ~IsolatedContext();
 
+  // Unregisters a file system of given |filesystem_id|. Must be called with
+  // lock_ held.  Returns true if the file system is unregistered.
+  bool UnregisterFileSystem(const std::string& filesystem_id);
+
   // Returns a new filesystem_id.  Called with lock.
   std::string GetNewFileSystemId() const;