Implement a new flow event API that allows binding flow events and regular events.

ipc/ipc_channel_reader.cc

Index: ipc/ipc_channel_reader.cc
diff --git a/ipc/ipc_channel_reader.cc b/ipc/ipc_channel_reader.cc
index f41a0d7737e4656cd279db0de8ef83c2b9e9fbaa..8bae2263a3ae010b92b5d750904eee39d2b7995b 100644
--- a/ipc/ipc_channel_reader.cc
+++ b/ipc/ipc_channel_reader.cc
@@ -82,10 +82,12 @@ bool ChannelReader::DispatchInputData(const char* input_data,
 #ifdef IPC_MESSAGE_LOG_ENABLED
       std::string name;
       Logging::GetInstance()->GetMessageText(m.type(), &name, &m, NULL);
-      TRACE_EVENT1("ipc,toplevel", "ChannelReader::DispatchInputData",
+      TRACE_EVENT_WITH_FLOW1("ipc,toplevel", "ChannelReader::DispatchInputData",
+                   m.flags(), TRACE_EVENT_FLAG_FLOW_IN,
                    "name", name);
 #else
-      TRACE_EVENT2("ipc,toplevel", "ChannelReader::DispatchInputData",
+      TRACE_EVENT_WITH_FLOW2("ipc,toplevel", "ChannelReader::DispatchInputData",
+                   m.flags(), TRACE_EVENT_FLAG_FLOW_IN,
                    "class", IPC_MESSAGE_ID_CLASS(m.type()),
                    "line", IPC_MESSAGE_ID_LINE(m.type()));
 #endif