Add a mode flag to the tracing framework.

components/tracing/tracing_messages.h

 // 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.
 
 // Multiply-included message header, no traditional include guard.
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/debug/trace_event.h"
 #include "base/sync_socket.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_message_utils.h"
 #include "ipc/ipc_platform_file.h"
 
 #define IPC_MESSAGE_START TracingMsgStart
 
 // Sent to all child processes to enable trace event recording.
-IPC_MESSAGE_CONTROL3(TracingMsg_BeginTracing,
+IPC_MESSAGE_CONTROL4(TracingMsg_BeginTracing,
                      std::vector<std::string> /* included_categories */,
                      std::vector<std::string> /* excluded_categories */,
-                     base::TimeTicks /* browser_time */)
+                     base::TimeTicks /* browser_time */,
+                     int /* base::debug::TraceMode */)
 
 // Sent to all child processes to disable trace event recording.
 IPC_MESSAGE_CONTROL0(TracingMsg_EndTracing)
 
 // Sent to all child processes to get trace buffer fullness.
 IPC_MESSAGE_CONTROL0(TracingMsg_GetTraceBufferPercentFull)
 
 // Sent to all child processes to set watch event.
 IPC_MESSAGE_CONTROL2(TracingMsg_SetWatchEvent,
                      std::string /* category_name */,
@@ skipping 14 matching lines @@
                      int /* base::debug::TraceLog::Notification */)
 
 // Child processes send trace data back in JSON chunks.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TraceDataCollected,
                      std::string /*json trace data*/)
 
 // Reply to TracingMsg_GetTraceBufferPercentFull.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TraceBufferPercentFullReply,
                      float /*trace buffer percent full*/)