Make OperationID usable for error handling.

webkit/browser/fileapi/file_system_operation_runner.h

Index: webkit/browser/fileapi/file_system_operation_runner.h
diff --git a/webkit/browser/fileapi/file_system_operation_runner.h b/webkit/browser/fileapi/file_system_operation_runner.h
index 3b36c4333f74f4b8dc525a7e997bfe4a6f71b180..f00cb0b1744d5057735d5982ca6d4257dcb4cd1b 100644
--- a/webkit/browser/fileapi/file_system_operation_runner.h
+++ b/webkit/browser/fileapi/file_system_operation_runner.h
@@ -27,7 +27,7 @@ class FileSystemContext;
 // A central interface for running FileSystem API operations.
 // All operation methods take callback and returns OperationID, which is
 // an integer value which can be used for cancelling an operation.
-// All operation methods return kErrorOperationID if running (posting) an
+// All operation methods return valid OperationID even if running (posting) an
 // operation fails, in addition to dispatching the callback with an error
 // code (therefore in most cases the caller does not need to check the
 // returned operation ID).
@@ -43,8 +43,6 @@ class WEBKIT_STORAGE_BROWSER_EXPORT FileSystemOperationRunner
 
   typedef int OperationID;
 
-  static const OperationID kErrorOperationID;
-
   virtual ~FileSystemOperationRunner();
 
   // Cancels all inflight operations.