Reland "Throttle resource message requests during user interaction"

content/child/resource_dispatcher.h

Index: content/child/resource_dispatcher.h
diff --git a/content/child/resource_dispatcher.h b/content/child/resource_dispatcher.h
index 1e646fb8450c3ac94fa5720a2be24bbbdb9abfff..ce21c3b0fa772dce9fdb7d31a2d964bd69574d4d 100644
--- a/content/child/resource_dispatcher.h
+++ b/content/child/resource_dispatcher.h
@@ -99,6 +99,12 @@ class CONTENT_EXPORT ResourceDispatcher : public IPC::Listener {
       const ResourceMsg_RequestCompleteData& request_complete_data,
       const base::TimeTicks& renderer_completion_time);
 
+  void set_message_sender(IPC::Sender* sender) {
+    DCHECK(sender);
+    DCHECK(pending_requests_.empty());
+    message_sender_ = sender;
+  }
+
   IPC::Sender* message_sender() const { return message_sender_; }
 
   // This does not take ownership of the delegate. It is expected that the