Add simple trace logging of received IPC messages

ipc/ipc_channel_proxy.cc

Index: ipc/ipc_channel_proxy.cc
diff --git a/ipc/ipc_channel_proxy.cc b/ipc/ipc_channel_proxy.cc
index f542eae2b0e59403560c4709afaf96f19ff8c6bf..62c1ecfda6fd9693eb80c9b981d265b8309707b1 100644
--- a/ipc/ipc_channel_proxy.cc
+++ b/ipc/ipc_channel_proxy.cc
@@ -4,6 +4,7 @@
 
 #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"
@@ -238,13 +239,21 @@ void ChannelProxy::Context::AddFilter(MessageFilter* filter) {
 
 // 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;