Navigation transitions: Block first response until after transitions have run.

content/common/transition_request_messages.h

Index: content/common/transition_request_messages.h
diff --git a/content/common/transition_request_messages.h b/content/common/transition_request_messages.h
new file mode 100644
index 0000000000000000000000000000000000000000..ca0f6e40a6bd0ccb0df46e86c366e2198156cc1d
--- /dev/null
+++ b/content/common/transition_request_messages.h
@@ -0,0 +1,16 @@
+// Copyright 2014 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.
+
+// IPC messages for page rendering.
+// Multiply-included message file, no include guard.
+
+#include "base/memory/shared_memory.h"
+#include "content/public/common/common_param_traits.h"
+#include "ipc/ipc_message_macros.h"
+
+#define IPC_MESSAGE_START TransitionRequestMsgStart
+
+// Messages sent from the renderer to the browser.
+IPC_MESSAGE_ROUTED1(TransitionRequestHostMsg_SetHasPendingTransitionRequest,
+                    bool  /* is_transition */)