[tracing] Send smaps file desciptor to child process for tracing

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/metrics/histogram.h"
 #include "base/sync_socket.h"
 #include "base/trace_event/memory_dump_request_args.h"
 #include "base/trace_event/trace_event_impl.h"
 #include "components/tracing/tracing_export.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"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT TRACING_EXPORT
 #define IPC_MESSAGE_START TracingMsgStart
 
 IPC_STRUCT_TRAITS_BEGIN(base::trace_event::TraceLogStatus)
-IPC_STRUCT_TRAITS_MEMBER(event_capacity)
-IPC_STRUCT_TRAITS_MEMBER(event_count)
+  IPC_STRUCT_TRAITS_MEMBER(event_capacity)
+  IPC_STRUCT_TRAITS_MEMBER(event_count)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_BEGIN(TracingMsg_MemoryTracingInfo)
+  IPC_STRUCT_MEMBER(uint64, tracing_process_id)
+  IPC_STRUCT_MEMBER(IPC::PlatformFileForTransit, smaps_fd)
+  IPC_STRUCT_MEMBER(IPC::PlatformFileForTransit, status_fd)
+IPC_STRUCT_END()
+
 IPC_STRUCT_TRAITS_BEGIN(base::trace_event::MemoryDumpRequestArgs)
-IPC_STRUCT_TRAITS_MEMBER(dump_guid)
-IPC_STRUCT_TRAITS_MEMBER(dump_type)
-IPC_STRUCT_TRAITS_MEMBER(level_of_detail)
+  IPC_STRUCT_TRAITS_MEMBER(dump_guid)
+  IPC_STRUCT_TRAITS_MEMBER(dump_type)
+  IPC_STRUCT_TRAITS_MEMBER(level_of_detail)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(base::trace_event::MemoryDumpArgs)
   IPC_STRUCT_TRAITS_MEMBER(level_of_detail)
 IPC_STRUCT_TRAITS_END()
 
 IPC_ENUM_TRAITS_MAX_VALUE(base::trace_event::MemoryDumpLevelOfDetail,
                           base::trace_event::MemoryDumpLevelOfDetail::LAST)
 
 IPC_ENUM_TRAITS_MAX_VALUE(
     base::trace_event::MemoryDumpType,
     static_cast<int>(base::trace_event::MemoryDumpType::LAST))
 
 // Sent to all child processes to enable trace event recording.
-IPC_MESSAGE_CONTROL3(TracingMsg_BeginTracing,
-                     std::string /*  trace_config_str */,
-                     base::TraceTicks /* browser_time */,
-                     uint64 /* Tracing process id (hash of child id) */)
+IPC_MESSAGE_CONTROL3(
+    TracingMsg_BeginTracing,
+    std::string /*  trace_config_str */,
+    base::TraceTicks /* browser_time */,
+    TracingMsg_MemoryTracingInfo /* child process' memory tracing info */)
 
 // Sent to all child processes to disable trace event recording.
 IPC_MESSAGE_CONTROL0(TracingMsg_EndTracing)
 
 // Sent to all child processes to cancel trace event recording.
 IPC_MESSAGE_CONTROL0(TracingMsg_CancelTracing)
 
 // Sent to all child processes to start monitoring.
 IPC_MESSAGE_CONTROL2(TracingMsg_EnableMonitoring,
                      std::string /*  trace_config_str */,
@@ skipping 65 matching lines @@
 IPC_MESSAGE_CONTROL1(TracingHostMsg_GlobalMemoryDumpRequest,
                      base::trace_event::MemoryDumpRequestArgs)
 
 // Reply to TracingMsg_ProcessMemoryDumpRequest.
 IPC_MESSAGE_CONTROL2(TracingHostMsg_ProcessMemoryDumpResponse,
                      uint64 /* dump_guid */,
                      bool /* success */)
 
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TriggerBackgroundTrace,
                      std::string /* name */)