PlzNavigate: Enforce 'form-action' CSP on the browser-side.

content/common/frame_messages.h

 // Copyright 2013 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 interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 343 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(headers)
   IPC_STRUCT_TRAITS_MEMBER(load_flags)
   IPC_STRUCT_TRAITS_MEMBER(has_user_gesture)
   IPC_STRUCT_TRAITS_MEMBER(skip_service_worker)
   IPC_STRUCT_TRAITS_MEMBER(request_context_type)
   IPC_STRUCT_TRAITS_MEMBER(mixed_content_context_type)
   IPC_STRUCT_TRAITS_MEMBER(searchable_form_url)
   IPC_STRUCT_TRAITS_MEMBER(searchable_form_encoding)
   IPC_STRUCT_TRAITS_MEMBER(initiator_origin)
   IPC_STRUCT_TRAITS_MEMBER(client_side_redirect_url)
+  IPC_STRUCT_TRAITS_MEMBER(is_form_submission)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(content::StartNavigationParams)
   IPC_STRUCT_TRAITS_MEMBER(extra_headers)
   IPC_STRUCT_TRAITS_MEMBER(transferred_request_child_id)
   IPC_STRUCT_TRAITS_MEMBER(transferred_request_request_id)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(content::NavigationTiming)
   IPC_STRUCT_TRAITS_MEMBER(redirect_start)
@@ skipping 1255 matching lines @@
                     int /* nfr_request_id */,
                     float /* distance */)
 
 IPC_MESSAGE_ROUTED0(FrameHostMsg_NavigationHandledByEmbedder)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.