If the renderer drops a navigation, make sure the spinner doesn't spin endlessly.

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 560 matching lines @@
                     FrameHostMsg_DidCommitProvisionalLoad_Params)
 
 // Notifies the browser that a document has been loaded.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidFinishDocumentLoad)
 
 IPC_MESSAGE_ROUTED3(FrameHostMsg_DidFailLoadWithError,
                     GURL /* validated_url */,
                     int /* error_code */,
                     base::string16 /* error_description */)
 
+// Sent when the renderer decides to ignore a navigation.
+IPC_MESSAGE_ROUTED0(FrameHostMsg_DidDropNavigation)
+
 // Sent when the renderer starts loading the page. |to_different_document| will
 // be true unless the load is a fragment navigation, or triggered by
 // history.pushState/replaceState.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_DidStartLoading,
                     bool /* to_different_document */)
 
 // Sent when the renderer is done loading a page.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidStopLoading)
 
 // Sent when the renderer changed the progress of a load.
@@ skipping 213 matching lines @@
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidFirstVisuallyNonEmptyPaint)
 
 #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