Add WasShown/WasHidden to RenderFrameObserver.

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index a62b7f8cd18f1ac9a9a4f9aa57a18f1fad49ce28..55580ceeae312bdbc57bcbdea35600aa25ac6377 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -19,6 +19,7 @@
 #include "content/browser/renderer_host/input/input_router.h"
 #include "content/browser/renderer_host/input/timeout_monitor.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/common/desktop_notification_messages.h"
 #include "content/common/frame_messages.h"
 #include "content/common/input_messages.h"
@@ -488,6 +489,10 @@ void RenderFrameHostImpl::OnNavigate(const IPC::Message& msg) {
   frame_tree_node()->navigator()->DidNavigate(this, validated_params);
 }
 
+RenderWidgetHostImpl* RenderFrameHostImpl::GetRenderWidgetHost() {
+  return static_cast<RenderWidgetHostImpl*>(render_view_host_);
+}
+
 int RenderFrameHostImpl::GetEnabledBindings() {
   return render_view_host_->GetEnabledBindings();
 }