Add simple trace logging of received IPC messages

ipc/ipc_channel_proxy.cc

 // Copyright (c) 2011 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 "base/bind.h"
 #include "base/compiler_specific.h"
+#include "base/debug/trace_event.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_logging.h"
 #include "ipc/ipc_message_utils.h"
 
 namespace IPC {
 
 // This helper ensures the message is deleted if the task is deleted without
@@ skipping 214 matching lines @@
 // Called on the listener's thread
 void ChannelProxy::Context::AddFilter(MessageFilter* filter) {
   base::AutoLock auto_lock(pending_filters_lock_);
   pending_filters_.push_back(make_scoped_refptr(filter));
   ipc_message_loop_->PostTask(
       FROM_HERE, base::Bind(&Context::OnAddFilter, this));
 }
 
 // Called on the listener's thread
 void ChannelProxy::Context::OnDispatchMessage(const Message& message) {
+  std::string name = "N/A (IPC Logging disabled)";

[jbates, 2012/02/13 23:26:25]

To avoid the overhead of this string, I would move it inside the
IPC_MESSAGE_LOG_ENABLED ifdef, and have two forms of TRACE_EVENTs: one with
"name" in the #ifdef and one without in the #else. (std::string arguments are
expensive with tracing since they require an allocation and copy for every event
even though it's the same string every time in this case.)

+#ifdef IPC_MESSAGE_LOG_ENABLED
+  Logging* logger = Logging::GetInstance();
+  logger->GetMessageText(message.type(), &name, &message, NULL);
+#endif
+  TRACE_EVENT2("task", "ChannelProxy::Context::OnDispatchMessage",
+               "type", message.type(),
+               "name", name);
+
   if (!listener_)
     return;
 
   OnDispatchConnected();
 
 #ifdef IPC_MESSAGE_LOG_ENABLED
-  Logging* logger = Logging::GetInstance();
   if (message.type() == IPC_LOGGING_ID) {
     logger->OnReceivedLoggingMessage(message);
     return;
   }
 
   if (logger->Enabled())
     logger->OnPreDispatchMessage(message);
 #endif
 
   listener_->OnMessageReceived(message);
@@ skipping 138 matching lines @@
   Channel* channel = context_.get()->channel_.get();
   // Channel must have been created first.
   DCHECK(channel) << context_.get()->channel_id_;
   return channel->GetClientEuid(client_euid);
 }
 #endif
 
 //-----------------------------------------------------------------------------
 
 }  // namespace IPC