PlzNavigate: Show error pages when the navigation failed before commit

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 "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/common/frame_message_enums.h"
@@ skipping 515 matching lines @@
 // PlzNavigate
 // Tells the renderer that a navigation is ready to commit.  The renderer should
 // request |stream_url| to get access to the stream containing the body of the
 // response.
 IPC_MESSAGE_ROUTED4(FrameMsg_CommitNavigation,
                     content::ResourceResponseHead,   /* response */
                     GURL,                            /* stream_url */
                     content::CommonNavigationParams, /* common_params */
                     content::RequestNavigationParams /* request_params */)
 
+// PlzNavigate
+// Tells the renderer that a navigation failed with the error code |error_code|
+// and that the renderer should display an appropriate error page.
+IPC_MESSAGE_ROUTED4(FrameMsg_FailedNavigation,
+                    content::CommonNavigationParams,  /* common_params */
+                    content::RequestNavigationParams, /* request_params */
+                    bool,                             /* stale_copy_in_cache */
+                    int /* error_code */)

[Charlie Reis, 2015/04/09 00:07:30]

Shouldn't this comment line up with the others, as in request_params on the
struct above?  Or we could match the other structs where the comments aren't
lined up.  Let's pick one or the other, though.

[clamy, 2015/04/10 14:04:49]

Done. Weirdly this is produced by git cl format.

+
 #if defined(ENABLE_PLUGINS)
 // Notifies the renderer of updates to the Plugin Power Saver origin whitelist.
 IPC_MESSAGE_ROUTED1(FrameMsg_UpdatePluginContentOriginWhitelist,
                     std::set<GURL> /* origin_whitelist */)
 #endif  // defined(ENABLE_PLUGINS)
 
 // -----------------------------------------------------------------------------
 // Messages sent from the renderer to the browser.
 
 // Blink and JavaScript error messages to log to the console
@@ skipping 308 matching lines @@
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DispatchLoad)
 
 #if defined(OS_MACOSX) || defined(OS_ANDROID)
 
 // Message to show/hide a popup menu using native controls.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_ShowPopup,
                     FrameHostMsg_ShowPopup_Params)
 IPC_MESSAGE_ROUTED0(FrameHostMsg_HidePopup)
 
 #endif