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

base/trace_event/process_memory_maps_dump_provider.h

Index: base/trace_event/process_memory_maps_dump_provider.h
diff --git a/base/trace_event/process_memory_maps_dump_provider.h b/base/trace_event/process_memory_maps_dump_provider.h
index f302a48dd7da182f587545e929f75ed3f91baf97..2a046fa01824e7e007c44d66ceffdb659a2947f8 100644
--- a/base/trace_event/process_memory_maps_dump_provider.h
+++ b/base/trace_event/process_memory_maps_dump_provider.h
@@ -5,6 +5,7 @@
 #ifndef BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_
 #define BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_
 
+#include "base/files/scoped_file.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/singleton.h"
 #include "base/trace_event/memory_dump_provider.h"
@@ -21,12 +22,18 @@ class BASE_EXPORT ProcessMemoryMapsDumpProvider : public MemoryDumpProvider {
   bool OnMemoryDump(const MemoryDumpArgs& args,
                     ProcessMemoryDump* pmd) override;
 
+#if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_NACL)
+  void set_smaps_file(FILE* file) { smaps_file_.reset(file); }
+#endif
+
  private:
   friend struct DefaultSingletonTraits<ProcessMemoryMapsDumpProvider>;
   FRIEND_TEST_ALL_PREFIXES(ProcessMemoryMapsDumpProviderTest, ParseProcSmaps);
 
 #if defined(OS_LINUX) || defined(OS_ANDROID) || defined(OS_NACL)
   static FILE* proc_smaps_for_testing;
+
+  ScopedFILE smaps_file_;
 #endif
 
   ProcessMemoryMapsDumpProvider();