Revert of OOPIF: Specify previous sibling frames when creating new RenderFrames.

content/renderer/render_frame_impl.h

Index: content/renderer/render_frame_impl.h
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index 53eea0cfe07e06e624b817205ad817d04266bbda..0046c35071b46e922926faea9befdec48f6702b4 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -130,16 +130,14 @@
   // Creates a new RenderFrame with |routing_id| as a child of the RenderFrame
   // identified by |parent_routing_id| or as the top-level frame if the latter
   // is MSG_ROUTING_NONE. If |proxy_routing_id| is MSG_ROUTING_NONE, it creates
-  // the Blink WebLocalFrame and inserts it into the frame tree after the frame
-  // identified by |previous_sibling_routing_id|, or as the first child if
-  // |previous_sibling_routing_id| is MSG_ROUTING_NONE. Otherwise, the frame is
-  // semi-orphaned until it commits, at which point it replaces the proxy
-  // identified by |proxy_routing_id|. Note: This is called only when
-  // RenderFrame is being created in response to IPC message from the browser
-  // process. All other frame creation is driven through Blink and Create.
+  // the Blink WebLocalFrame and inserts it in the proper place in the frame
+  // tree. Otherwise, the frame is semi-orphaned until it commits, at which
+  // point it replaces the proxy identified by |proxy_routing_id|.
+  // Note: This is called only when RenderFrame is being created in response to
+  // IPC message from the browser process. All other frame creation is driven
+  // through Blink and Create.
   static void CreateFrame(int routing_id,
                           int parent_routing_id,
-                          int previous_sibling_routing_id,
                           int proxy_routing_id,
                           const FrameReplicationState& replicated_state,
                           CompositorDependencies* compositor_deps,