PlzNavigate: stop navigations when opening a document for write

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 0442702b4436d2608fba0d2c67efd19ed4c53bcb..7ddf5661d6648bbd67538c2d0aa1d186607efb5e 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -887,6 +887,11 @@ IPC_MESSAGE_ROUTED4(FrameMsg_CommitNavigation,
                     content::RequestNavigationParams  /* request_params */)
 
 // PlzNavigate
+// Informs the renderer that the browser stopped processing a renderer-initiated
+// navigation.
+IPC_MESSAGE_ROUTED0(FrameMsg_DroppedNavigation)

[Nate Chapin, 2017/03/07 18:39:08]

Are there any race conditions that could lead to dropping a subsequent
navigation instead of the intended one? I don't know how much to worry about
that case.

[nasko, 2017/03/09 05:19:28]

Would it help if we add the URL of the navigation the renderer wanted to cancel?
This gives us an extra piece of data to ensure we are cancelling the intended
navigation.

[clamy, 2017/03/13 13:55:57]

We could still have race condition though if we try to request a navigation to
the same url twice. Short of introducing an ID, there's not much to do to
prevent a race from happening.

+
+// 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,
@@ -1481,6 +1486,11 @@ IPC_MESSAGE_ROUTED2(FrameHostMsg_BeginNavigation,
                     content::CommonNavigationParams,
                     content::BeginNavigationParams)
 
+// PlzNavigate
+// Tells the browser to abort an ongoing renderer-initiated navigation. This is
+// used when the page calls document.open.
+IPC_MESSAGE_ROUTED0(FrameHostMsg_AbortNavigation)
+
 // Sent as a response to FrameMsg_VisualStateRequest.
 // The message is delivered using RenderWidget::QueueMessage.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_VisualStateResponse, uint64_t /* id */)