Revert my change to get the tree green. Not sure why the tests became flaky....

chrome/test/automation/automation_messages_internal.h

 // Copyright (c) 2006-2008 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.
 
 // Defines the IPC messages used by the automation interface.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
@@ skipping 13 matching lines @@
 //       which expect a response).  The routing_id shouldn't be used for
 //       any other purpose in these message types.
 
 // NOTE: All the new IPC messages should go at the end (before IPC_END_MESSAGES)
 //       The IPC message IDs are part of an enum and hence the value
 //       assumed to be constant across the builds may change.
 //       The messages AutomationMsg_WindowHWND* in particular should not change
 //       since the PageCyclerReferenceTest depends on the correctness of the
 //       message IDs across the builds.
 
-IPC_BEGIN_MESSAGES(Automation)
+// By using a start value of 0 for automation messages, we keep backward
+// compatability with old builds.
+IPC_BEGIN_MESSAGES(Automation, 0)
 
   // This message is fired when the AutomationProvider is up and running
   // in the app (the app is not fully up at this point).
   IPC_MESSAGE_ROUTED0(AutomationMsg_Hello)
 
   // This message is fired when the initial tab(s) are finished loading.
   IPC_MESSAGE_ROUTED0(AutomationMsg_InitialLoadsComplete)
 
   // This message notifies the AutomationProvider to append a new tab the window
   // with the given handle. The response contains the index of the new tab, or
@@ skipping 152 matching lines @@
                       int)  // status
 
   // Requests that the automation provider ask history for the most recent
   // chain of redirects coming from the given URL. The response must be
   // decoded by the caller manually; it contains an integer indicating the
   // number of URLs, followed by that many wstrings indicating a chain of
   // redirects. On failure, the count will be negative.
   IPC_MESSAGE_ROUTED2(AutomationMsg_RedirectsFromRequest,
                       int,   // tab handle
                       GURL)  // source URL
-  IPC_MESSAGE_ROUTED2(AutomationMsg_RedirectsFromResponse,
-                      bool /* succeeded */,
-                      std::vector<GURL> /* redirects */)
+  IPC_MESSAGE_EMPTY(AutomationMsg_RedirectsFromResponse)
 
   // This message asks the AutomationProvider whether a tab is waiting for
   // login info.
   IPC_MESSAGE_ROUTED1(AutomationMsg_NeedsAuthRequest,
                       int)  // tab handle
   IPC_MESSAGE_ROUTED1(AutomationMsg_NeedsAuthResponse,
                       bool)  // status
 
   // This message requests the AutomationProvider to apply a certain
   // accelerator. It is completely asynchronous with the resulting accelerator
@@ skipping 667 matching lines @@
                       std::wstring /* overrided encoding name */)
   IPC_MESSAGE_ROUTED1(AutomationMsg_OverrideEncodingResponse,
                       bool /* success */)
 
   // Used to disable the dialog box that prompts the user for a path when
   // saving a web page.
   IPC_MESSAGE_ROUTED1(AutomationMsg_SavePackageShouldPromptUser,
                       bool /* false if we want to not show the dialog */)
 
 IPC_END_MESSAGES(Automation)