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

content/browser/tracing/trace_message_filter.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 "content/browser/tracing/trace_message_filter.h"
 
 #include "components/tracing/tracing_messages.h"
 #include "content/browser/tracing/background_tracing_manager_impl.h"
 #include "content/browser/tracing/tracing_controller_impl.h"
 #include "content/common/child_process_host_impl.h"
 
+#if defined(OS_LINUX)
+#include <fcntl.h>
+#endif
+
+namespace {
+
+void OpenFilesForProcess(int pid,
+                         TracingMsg_MemoryTracingInfo& memory_tracing_info) {
+#if defined(OS_LINUX)
+  std::string proc_smaps_name = base::StringPrintf("/proc/%d/smaps", pid);
+  int smaps_fd = HANDLE_EINTR(open(proc_smaps_name.c_str(), O_RDONLY));
+  if (smaps_fd != -1) {
+    memory_tracing_info.smaps_fd = IPC::GetFileHandleForProcess(
+        smaps_fd, base::GetCurrentProcessHandle(), true);
+  }
+
+  std::string proc_status_name = base::StringPrintf("/proc/%d/status", pid);
+  int status_fd = HANDLE_EINTR(open(proc_status_name.c_str(), O_RDONLY));
+  if (status_fd != -1) {
+    memory_tracing_info.status_fd = IPC::GetFileHandleForProcess(
+        status_fd, base::GetCurrentProcessHandle(), true);
+  }
+#endif
+}
+
+}  // namespace
+
 namespace content {
 
 TraceMessageFilter::TraceMessageFilter(int child_process_id)
     : BrowserMessageFilter(TracingMsgStart),
       has_child_(false),
       tracing_process_id_(
           ChildProcessHostImpl::ChildProcessUniqueIdToTracingProcessId(
               child_process_id)),
       is_awaiting_end_ack_(false),
       is_awaiting_capture_monitoring_snapshot_ack_(false),
@@ skipping 40 matching lines @@
                         OnProcessMemoryDumpResponse)
     IPC_MESSAGE_HANDLER(TracingHostMsg_TriggerBackgroundTrace,
                         OnTriggerBackgroundTrace)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void TraceMessageFilter::SendBeginTracing(
       const base::trace_event::TraceConfig& trace_config) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  TracingMsg_MemoryTracingInfo memory_tracing_info;
+  if (trace_config.IsDetailedMemoryDumpEnabled()) {
+    if (trace_config.IsDetailedMemoryDumpEnabled()) {
+      OpenFilesForProcess(this->peer_pid(), memory_tracing_info);
+    }
+    memory_tracing_info.tracing_process_id = tracing_process_id_;
+  }
   Send(new TracingMsg_BeginTracing(
-      trace_config.ToString(), base::TraceTicks::Now(), tracing_process_id_));
+      trace_config.ToString(), base::TraceTicks::Now(), memory_tracing_info));
 }
 
 void TraceMessageFilter::SendEndTracing() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(!is_awaiting_end_ack_);
   is_awaiting_end_ack_ = true;
   Send(new TracingMsg_EndTracing);
 }
 
 void TraceMessageFilter::SendCancelTracing() {
@@ skipping 119 matching lines @@
                                                      bool success) {
   TracingControllerImpl::GetInstance()->OnProcessMemoryDumpResponse(
       this, dump_guid, success);
 }
 
 void TraceMessageFilter::OnTriggerBackgroundTrace(const std::string& name) {
   BackgroundTracingManagerImpl::GetInstance()->OnHistogramTrigger(name);
 }
 
 }  // namespace content