PlzNavigate: don't stop all loaders when renderer-initiated nav fails

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 897 matching lines @@
 // 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
+// Informs the renderer that the browser stopped processing a renderer-initiated
+// navigation.

[Charlie Reis, 2017/03/23 16:52:53]

Please clarify how this differs from FrameMsg_Stop (e.g., doesn't stop ongoing
loads in the current page).

+IPC_MESSAGE_ROUTED0(FrameMsg_DroppedNavigation)
+
+// 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 */)
 
 // PlzNavigate
 // Tells the renderer that a navigation was blocked because a content security
@@ skipping 722 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.