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 9df2d868a956157e3efa88f4091086dc61729002..85836379987dcd11e818e8f2f2cbfe3f84fd23ba 100644
--- a/content/child/resource_dispatcher.h
+++ b/content/child/resource_dispatcher.h
@@ -91,6 +91,12 @@ class CONTENT_EXPORT ResourceDispatcher : public IPC::Listener {
   bool AttachThreadedDataReceiver(
       int request_id, blink::WebThreadedDataReceiver* threaded_data_receiver);
 
+  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