Support custom message filtering on Mojo binding objects

mojo/public/cpp/bindings/lib/multiplex_router.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/public/cpp/bindings/lib/multiplex_router.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 268 matching lines @@
  private:
   explicit Task(Type in_type) : type(in_type) {}
 };
 
 MultiplexRouter::MultiplexRouter(
     bool set_interface_id_namesapce_bit,
     ScopedMessagePipeHandle message_pipe,
     scoped_refptr<base::SingleThreadTaskRunner> runner)
     : set_interface_id_namespace_bit_(set_interface_id_namesapce_bit),
       task_runner_(runner),
-      header_validator_(this),
+      header_validator_(nullptr),
+      filters_(this),
       connector_(std::move(message_pipe),
                  Connector::MULTI_THREADED_SEND,
                  std::move(runner)),
       control_message_handler_(this),
       control_message_proxy_(&connector_),
       next_interface_id_value_(1),
       posted_to_process_tasks_(false),
       encountered_error_(false),
       paused_(false),
       testing_mode_(false) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   // Always participate in sync handle watching, because even if it doesn't
   // expect sync requests during sync handle watching, it may still need to
   // dispatch messages to associated endpoints on a different thread.
   connector_.AllowWokenUpBySyncWatchOnSameThread();
-  connector_.set_incoming_receiver(&header_validator_);
+  connector_.set_incoming_receiver(&filters_);
   connector_.set_connection_error_handler(
       base::Bind(&MultiplexRouter::OnPipeConnectionError,
                  base::Unretained(this)));
+
+  std::unique_ptr<MessageHeaderValidator> header_validator =
+      base::MakeUnique<MessageHeaderValidator>();
+  header_validator_ = header_validator.get();
+  filters_.Append(std::move(header_validator));
 }
 
 MultiplexRouter::~MultiplexRouter() {
   base::AutoLock locker(lock_);
 
   sync_message_tasks_.clear();
   tasks_.clear();
 
   for (auto iter = endpoints_.begin(); iter != endpoints_.end();) {
     InterfaceEndpoint* endpoint = iter->second.get();
     // Increment the iterator before calling UpdateEndpointStateMayRemove()
     // because it may remove the corresponding value from the map.
     ++iter;
 
     DCHECK(endpoint->closed());
     UpdateEndpointStateMayRemove(endpoint, PEER_ENDPOINT_CLOSED);
   }
 
   DCHECK(endpoints_.empty());
 }
 
 void MultiplexRouter::SetMasterInterfaceName(const std::string& name) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  header_validator_.SetDescription(name + " [master] MessageHeaderValidator");
+  header_validator_->SetDescription(name + " [master] MessageHeaderValidator");
   control_message_handler_.SetDescription(
       name + " [master] PipeControlMessageHandler");
 }
 
 void MultiplexRouter::CreateEndpointHandlePair(
     ScopedInterfaceEndpointHandle* local_endpoint,
     ScopedInterfaceEndpointHandle* remote_endpoint) {
   base::AutoLock locker(lock_);
   uint32_t id = 0;
   do {
@@ skipping 534 matching lines @@
       *inserted = true;
   } else {
     endpoint = iter->second.get();
   }
 
   return endpoint;
 }
 
 }  // namespace internal
 }  // namespace mojo