Fix history_indexer.idl to stop from rebuilding it every time.

chrome/browser/history/history_indexer.idl

 // Copyright (c) 2008 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.
 
 import "oaidl.idl";
 import "ocidl.idl";
 
 [
   object,
   uuid(9C1100DD-51D4-4827-AE9F-3B8FAC4AED72),
@@ skipping 25 matching lines @@
   // This method is called by Chrome when the users delete their history.
   // |begin_time| - Represents the start time from which the history needs to be
   //                deleted. It is given in UTC.
   // |end_time| - Represents the end time until when the history needs to be
   //                deleted. It is given in UTC
   // If both begin_time and end_time are '0', full user history needs to be
   // deleted.
   HRESULT DeleteUserHistoryBetween([in] VARIANT begin_time,
                                    [in] VARIANT end_time);
 };
+
+
+// This dummy library statement enforces the creation of a history_indexer.tlb.
+// This is necessary since MSVC assumes a .idl always creates a .tlb. Otherwise,
+// this .idl is always recompiled, giving many engs a headache.
+[
+  uuid(A5C5B8BE-E7E5-4cb9-A13B-B063361E7B6D),
+  helpstring("Dummy library")
+]
+library history_indexerLib
+{
+};