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

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index 0b8b72b7a7884d3a220e595ecb4358e571c52e42..af8289f7c336a5888c948ca3e226e6d05b44e3f8 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -578,6 +578,9 @@ IPC_MESSAGE_ROUTED3(FrameHostMsg_DidFailLoadWithError,
                     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.