PlzNavigate: store POST data in the FrameNavigationEntry

content/browser/frame_host/navigation_request.h

Index: content/browser/frame_host/navigation_request.h
diff --git a/content/browser/frame_host/navigation_request.h b/content/browser/frame_host/navigation_request.h
index 7d3744c3b8c0ab67bee336ab407865ce78fc0911..fd171d18ff22568849b2a38d2ba2fa604d102351 100644
--- a/content/browser/frame_host/navigation_request.h
+++ b/content/browser/frame_host/navigation_request.h
@@ -159,6 +159,10 @@ class CONTENT_EXPORT NavigationRequest : public NavigationURLLoaderDelegate {
   void TransferNavigationHandleOwnership(
       RenderFrameHostImpl* render_frame_host);
 
+  // Resets the POST data for the navigation. This is called when encoutering a
+  // cross-site redirect.
+  void ResetPostData();

[Charlie Reis, 2016/05/11 00:00:23]

Lukasz found some useful info on this in the spec (which is quite surprising to
me).  Apparently POST data is preserved on 307 and 308 redirects (which stay
POST), regardless of origin.  302, 303, and 304 redirects are converted to GET
and lose POST data.

While I think it's crazy that sites might pass on their POST data cross-site
without realizing it, we should probably preserve Chrome's current behavior here
(once we verify that this is true in practice).  Not sure what implication that
has for this method.

[clamy, 2016/05/11 08:54:41]

Removed the function, since the current behavior can be matched in
NavigationReques internally. We may reintroduce it if we decide to have POST
data be reset cross-site when --site-per-process is enabled.

+
  private:
   NavigationRequest(FrameTreeNode* frame_tree_node,
                     const CommonNavigationParams& common_params,
@@ -226,6 +230,9 @@ class CONTENT_EXPORT NavigationRequest : public NavigationURLLoaderDelegate {
   bool is_view_source_;
   int bindings_;
 
+  // This is kept to be sent to the renderer on commit.
+  scoped_refptr<ResourceRequestBody> post_data_;
+
   // The type of SiteInstance associated with this navigation.
   AssociatedSiteInstanceType associated_site_instance_type_;