Make flow event traces disabled-by-default, and rename "ipc" and "task" categories to "toplevel"

ipc/ipc_channel_reader.cc

 // Copyright (c) 2012 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 "ipc/ipc_channel_reader.h"
 
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_logging.h"
 #include "ipc/ipc_message_macros.h"
 
@@ skipping 65 matching lines @@
     if (message_tail) {
       int len = static_cast<int>(message_tail - p);
       Message m(p, len);
       if (!WillDispatchInputMessage(&m))
         return false;
 
 #ifdef IPC_MESSAGE_LOG_ENABLED
       Logging* logger = Logging::GetInstance();
       std::string name;
       logger->GetMessageText(m.type(), &name, &m, NULL);
-      TRACE_EVENT1("ipc", "ChannelReader::DispatchInputData", "name", name);
+      TRACE_EVENT1("toplevel", "ChannelReader::DispatchInputData",
+                   "name", name);
 #else
-      TRACE_EVENT2("ipc", "ChannelReader::DispatchInputData",
+      TRACE_EVENT2("toplevel", "ChannelReader::DispatchInputData",
                    "class", IPC_MESSAGE_ID_CLASS(m.type()),
                    "line", IPC_MESSAGE_ID_LINE(m.type()));
 #endif
       m.TraceMessageEnd();
       if (IsInternalMessage(m))
         HandleInternalMessage(m);
       else
         listener_->OnMessageReceived(m);
       p = message_tail;
     } else {
       // Last message is partial.
       break;
     }
   }
 
   // Save any partial data in the overflow buffer.
   input_overflow_buf_.assign(p, end - p);
 
   if (input_overflow_buf_.empty() && !DidEmptyInputBuffers())
     return false;
   return true;
 }
 
 
 }  // namespace internal
 }  // namespace IPC