Move FrameMsg_NewFrame/NewFrameProxy to mojom

content/browser/frame_host/render_frame_proxy_host.cc

Index: content/browser/frame_host/render_frame_proxy_host.cc
diff --git a/content/browser/frame_host/render_frame_proxy_host.cc b/content/browser/frame_host/render_frame_proxy_host.cc
index 34f364fb4c58d6467cca527e8f49ad475ef08ea1..3a11b57bb1a2d5edf161a2acad33f61d74340b66 100644
--- a/content/browser/frame_host/render_frame_proxy_host.cc
+++ b/content/browser/frame_host/render_frame_proxy_host.cc
@@ -184,14 +184,12 @@ bool RenderFrameProxyHost::InitRenderFrameProxy() {
         site_instance_.get());
   }
 
-  Send(new FrameMsg_NewFrameProxy(routing_id_,
-                                  frame_tree_node_->frame_tree()
-                                      ->GetRenderViewHost(site_instance_.get())
-                                      ->GetRoutingID(),
-                                  opener_routing_id,
-                                  parent_routing_id,
-                                  frame_tree_node_
-                                      ->current_replication_state()));
+  int view_routing_id = frame_tree_node_->frame_tree()
+      ->GetRenderViewHost(site_instance_.get())->GetRoutingID();
+  static_cast<RenderProcessHostImpl*>(GetProcess())->GetRendererInterface()

[ncarter (slow), 2016/09/30 23:35:14]

RPH->RPHI is not a safe cast; very similar to the RenderThread/MockRenderThread
situation, MockRenderProcessHost is not a RenderProcessHostImpl. So, code that
does this kind of cast will crash -- or worse -- if executed from inside a
content_unittest. If this works today, it's just because we don't have
content_unittest coverage for this case.

Which is possibly not too surprising if it is the case for RenderFrameProxyHost,
which is pretty hard to exercise outside of a browsertest, but I suspect we are
going to need a solution to this pattern in general that avoids the bad  cast.

+      ->CreateFrameProxy(routing_id_, view_routing_id, opener_routing_id,
+                         parent_routing_id,
+                         frame_tree_node_->current_replication_state());
 
   render_frame_proxy_created_ = true;