drive: Fix a crash caused by an empty edit URL

chrome/browser/chromeos/gdata/drive_file_system.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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 471 matching lines @@
   // the client side.
   // |callback| must not be null.
   void MoveEntryToRootDirectoryLocally(const FileMoveCallback& callback,
                                        const FilePath& file_path,
                                        const FilePath& dir_path,
                                        GDataErrorCode status,
                                        const GURL& document_url);
 
   // Callback for DriveServiceInterface::DeleteDocument. Removes the entry with
   // |resource_id| from the local snapshot of the filesystem and the cache.
-  // |document_url| is unused. |callback| may be null.
+  // |document_url| is unused. |callback| must not be null.
   void RemoveResourceLocally(const FileOperationCallback& callback,
                              const std::string& resource_id,
                              GDataErrorCode status,
                              const GURL& document_url);
 
   // Callback when an entry is moved to another directory on the client side.
   // Notifies the directory change and runs |callback|.
   // |callback| may be null.
   void NotifyAndRunFileMoveCallback(
       const FileMoveCallback& callback,
@@ skipping 270 matching lines @@
 
   // Part of MoveOnUIThread(). Called after GetEntryInfoPairByPaths() is
   // complete. |callback| must not be null.
   void MoveOnUIThreadAfterGetEntryInfoPair(
     const FilePath& dest_file_path,
     const FileOperationCallback& callback,
     scoped_ptr<EntryInfoPairResult> result);
 
   // Part of RemoveOnUIThread(). Called after GetEntryInfoByPath() is
   // complete.
+  // |callback| must not be null.
   void RemoveOnUIThreadAfterGetEntryInfo(
       const FileOperationCallback& callback,
       DriveFileError error,
       scoped_ptr<DriveEntryProto> entry_proto);
 
   // Part of RequestDirectoryRefreshOnUIThread(). Called after
   // GetEntryInfoByPath() is complete.
   void RequestDirectoryRefreshOnUIThreadAfterGetEntryInfo(
       const FilePath& file_path,
       DriveFileError error,
@@ skipping 65 matching lines @@
   // invalidate the weak pointers before any other members are destroyed.
   base::WeakPtrFactory<DriveFileSystem> ui_weak_ptr_factory_;
   // Unlike other classes, we need this as we need this to redirect a task
   // from IO thread to UI thread.
   base::WeakPtr<DriveFileSystem> ui_weak_ptr_;
 };
 
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_H_