Add WasShown/WasHidden to RenderFrameObserver.

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 835f6e70841288bd6687f9aad5693a266f498d2e..ab32d9f767fcf9484a1f3bcc7632f7b80a9152e5 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -39,6 +39,7 @@ class RenderFrameHostDelegate;
 class RenderFrameProxyHost;
 class RenderProcessHost;
 class RenderViewHostImpl;
+class RenderWidgetHostImpl;
 struct ContextMenuParams;
 struct GlobalRequestID;
 struct Referrer;
@@ -80,6 +81,9 @@ class CONTENT_EXPORT RenderFrameHostImpl : public RenderFrameHost {
   RenderViewHostImpl* render_view_host() { return render_view_host_; }
   RenderFrameHostDelegate* delegate() { return delegate_; }
   FrameTreeNode* frame_tree_node() { return frame_tree_node_; }
+  // TODO(nasko): The RenderWidgetHost will be owned by RenderFrameHost in
+  // the future, so update this accessor to return the right pointer.
+  RenderWidgetHostImpl* GetRenderWidgetHost();
 
   // This function is called when this is a swapped out RenderFrameHost that
   // lives in the same process as the parent frame. The