Fix support for multiple frames per SiteInstance in CreateProxiesForSiteInstance

content/browser/frame_host/frame_tree.cc

Index: content/browser/frame_host/frame_tree.cc
diff --git a/content/browser/frame_host/frame_tree.cc b/content/browser/frame_host/frame_tree.cc
index 90c1f8d343f56497862403d4ee851bc913ea3480..0f679e8ca6088e80e5eff32f9c37a772f603acd1 100644
--- a/content/browser/frame_host/frame_tree.cc
+++ b/content/browser/frame_host/frame_tree.cc
@@ -54,7 +54,13 @@ bool ResetNodesForNewProcess(RenderViewHost* render_view_host,
 
 bool CreateProxyForSiteInstance(const scoped_refptr<SiteInstance>& instance,
                                 FrameTreeNode* node) {
-  node->render_manager()->CreateRenderFrameProxy(instance.get());
+  // If a new frame is created in an existing SiteInstance, the other frames in
+  // that SiteInstance don't need a proxy for the new frame.
+  SiteInstance* current_instance =
+      node->render_manager()->current_frame_host()->GetSiteInstance();

[Charlie Reis, 2014/10/21 22:31:27]

What about the SiteInstances that already have RenderFrameProxyHosts on the
proxy_hosts_ list?  Those would also qualify as "existing SiteInstance."

+  if (current_instance != instance.get()) {

[nasko, 2014/10/21 22:25:23]

nit: one line if statements don't need {}

+    node->render_manager()->CreateRenderFrameProxy(instance.get());
+  }
   return true;
 }