Move SwapOut methods to RenderFrameHost.

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index 99d0c43b56c14fd87a1740fbfd3dd6fc3409b8d5..52d43a35b29df1c79501e9c4a2e91fad7d2a8407 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -125,9 +125,14 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost {
       PageTransition page_transition,
       bool should_replace_current_entry);
 
-  // Hack to get this subframe to swap out, without yet moving over all the
-  // SwapOut state and machinery from RenderViewHost.
+  // Tells the renderer that this RenderFrame is being swapped out for one in a
+  // different renderer process.  It should run its unload handler and move to
+  // a blank document.  The renderer should preserve the Frame object until it
+  // exits, in case we come back.  The renderer can exit if it has no other
+  // active RenderFrames, but not until WasSwappedOut is called (when it is no
+  // longer visible).
   void SwapOut();
+
   void OnSwappedOut(bool timed_out);
   bool is_swapped_out() { return is_swapped_out_; }
   void set_swapped_out(bool is_swapped_out) {