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

base/trace_event/process_memory_maps_dump_provider.h

 // Copyright 2015 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.
 
 #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"
 
 namespace base {
 namespace trace_event {
 
 // Dump provider which collects process-wide memory stats.
 class BASE_EXPORT ProcessMemoryMapsDumpProvider : public MemoryDumpProvider {
  public:
   static ProcessMemoryMapsDumpProvider* GetInstance();
 
   // MemoryDumpProvider implementation.
   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();
   ~ProcessMemoryMapsDumpProvider() override;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessMemoryMapsDumpProvider);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_PROCESS_MEMORY_MAPS_DUMP_PROVIDER_H_