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

components/tracing/child_memory_dump_manager_delegate_impl.cc

Index: components/tracing/child_memory_dump_manager_delegate_impl.cc
diff --git a/components/tracing/child_memory_dump_manager_delegate_impl.cc b/components/tracing/child_memory_dump_manager_delegate_impl.cc
index fe5c952f6a9a91ecf83ce42e81e49b543eb42974..104c013108210067df846d3e6cb373f5c73eaee0 100644
--- a/components/tracing/child_memory_dump_manager_delegate_impl.cc
+++ b/components/tracing/child_memory_dump_manager_delegate_impl.cc
@@ -5,6 +5,8 @@
 #include "components/tracing/child_memory_dump_manager_delegate_impl.h"
 
 #include "base/single_thread_task_runner.h"
+#include "base/trace_event/process_memory_maps_dump_provider.h"
+#include "base/trace_event/process_memory_totals_dump_provider.h"
 #include "components/tracing/child_trace_message_filter.h"
 
 namespace tracing {
@@ -90,6 +92,37 @@ void ChildMemoryDumpManagerDelegateImpl::RequestGlobalMemoryDump(
   ctmf_->SendGlobalMemoryDumpRequest(args, callback);
 }
 
+void ChildMemoryDumpManagerDelegateImpl::SetMemoryTracingInfo(
+    const TracingMsg_MemoryTracingInfo& memory_tracing_info) {
+  // Checks if id is not reset to different one.
+  DCHECK_IMPLIES(
+      tracing_process_id_ !=
+          base::trace_event::MemoryDumpManager::kInvalidTracingProcessId,
+      memory_tracing_info.tracing_process_id == tracing_process_id_);
+  tracing_process_id_ = memory_tracing_info.tracing_process_id;
+
+#if defined(OS_LINUX)
+  base::trace_event::ProcessMemoryMapsDumpProvider::GetInstance()
+      ->set_smaps_file(fdopen(IPC::PlatformFileForTransitToPlatformFile(
+                                  memory_tracing_info.smaps_fd),
+                              "r"));
+  base::trace_event::ProcessMemoryTotalsDumpProvider::GetInstance()
+      ->set_proc_status_fd(IPC::PlatformFileForTransitToPlatformFile(
+          memory_tracing_info.status_fd));
+#endif
+}
+
+void ChildMemoryDumpManagerDelegateImpl::ResetMemoryTracingInfo() {
+#if defined(OS_LINUX)
+  tracing_process_id_ =
+      base::trace_event::MemoryDumpManager::kInvalidTracingProcessId;
+  base::trace_event::ProcessMemoryMapsDumpProvider::GetInstance()
+      ->set_smaps_file(nullptr);
+  base::trace_event::ProcessMemoryTotalsDumpProvider::GetInstance()
+      ->reset_proc_status_fd();
+#endif
+}
+
 uint64 ChildMemoryDumpManagerDelegateImpl::GetTracingProcessId() const {
   return tracing_process_id_;
 }