Make RenderFrame{Host} objects routable.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index d30295dd1177d90efaa4a3244ef7d946b004384f..64912afd6b9d4195da1b8b35f156e18bbbcfd8cb 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1615,6 +1615,17 @@ void WebContentsImpl::ShowCreatedWidget(int route_id,
   RenderWidgetHostImpl* render_widget_host_impl =
       RenderWidgetHostImpl::From(widget_host_view->GetRenderWidgetHost());
   render_widget_host_impl->Init();

[Charlie Reis, 2013/08/26 18:27:10]

Is this the only place Init is being called?

I'm trying to think of a more elegant way to ensure that RFH::Init() is called
at the same time.  One option is making RWH::Init() virtual and overriding it in
RVH to initialize itself and then its RFH.

[awong, 2013/08/27 19:58:13]

For now.  When we create subframes, we'll need to call RFH::Init() too on all of
them.
Yeah, I struggled with this. Inheritance is cleaner in the sense that the RVH is
initializing itself.  On the down side, it also widens the interface to RWH. 
Seeing code like

RenderViewHost::Init {
  RenderWidgetHost::Init();
  main_render_frame_host()->Init();
}

made me uneasy.

Another option is to add a RVH::InitMainFrame() that's non-virtual.  We still
need to call it here, but at least RVH is still responsible for initializing its
own mainframe.

I didn't like any of these setups.  If you prefer inheritance, I'm happy to
that.

Update: as per in-person discussion, made RenderWidgetHost::Init virtual.

+  if (render_widget_host_impl->IsRenderView()) {
+    // The mainframe RenderFrameHost for a RenderViewHost has its

[Charlie Reis, 2013/08/26 18:27:10]

nit: main frame
(here and below)

[awong, 2013/08/27 19:58:13]

Done.

+    // initialization delayed until the containing RenderViewHost itself is
+    // initialized. When the containing RenderViewHost is initialized, the
+    // mainframe should also needs to be explicitly initialized. This is not

[Charlie Reis, 2013/08/26 18:27:10]

nit: Remove "should"

[awong, 2013/08/27 19:58:13]

Done.

+    // an issue for subframe RenderFrameHosts.

[Charlie Reis, 2013/08/26 18:27:10]

Can you explain why in the comment?  I'm not sure why the initialization differs
between main frame and subframe RFHs.

[awong, 2013/08/27 19:58:13]

Done.

+    RenderViewHostImpl* render_view_host_impl =
+        static_cast<RenderViewHostImpl*>(
+            RenderWidgetHostImpl::From(render_widget_host_impl));
+    render_view_host_impl->main_render_frame_host()->Init();
+  }
   // Only allow privileged mouse lock for fullscreen render widget, which is
   // used to implement Pepper Flash fullscreen.
   render_widget_host_impl->set_allow_privileged_mouse_lock(is_fullscreen);