Add ref-count on RenderViewHost for each new RenderFrameProxyHost.

content/browser/frame_host/render_frame_proxy_host.h

Index: content/browser/frame_host/render_frame_proxy_host.h
diff --git a/content/browser/frame_host/render_frame_proxy_host.h b/content/browser/frame_host/render_frame_proxy_host.h
index 9594f75010a3ef2cc247eba06fd7435be42b4aa9..c297c043a0f4f6a077f49fa9a00bdfb3f9ee240e 100644
--- a/content/browser/frame_host/render_frame_proxy_host.h
+++ b/content/browser/frame_host/render_frame_proxy_host.h
@@ -60,6 +60,7 @@ class RenderFrameProxyHost
   static RenderFrameProxyHost* FromID(int process_id, int routing_id);
 
   RenderFrameProxyHost(SiteInstance* site_instance,
+                       RenderViewHostImpl* render_view_host,
                        FrameTreeNode* frame_tree_node);
   ~RenderFrameProxyHost() override;
 
@@ -149,6 +150,11 @@ class RenderFrameProxyHost
   // RenderFrameHosts. See https://crbug.com/357747.
   scoped_ptr<RenderFrameHostImpl> render_frame_host_;
 
+  // The RenderViewHost that this RenderFrameProxyHost is associated with. It is
+  // kept alive as long as any RenderFrameHosts or RenderFrameProxyHosts
+  // are associated with it.
+  RenderViewHostImpl* render_view_host_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderFrameProxyHost);
 };