[tracing] Dump child processes' memory metrics in browser

base/trace_event/process_memory_maps_dump_provider.cc

 // 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.
 
 #include "base/trace_event/process_memory_maps_dump_provider.h"
 
 #include "base/files/scoped_file.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
@@ skipping 118 matching lines @@
         }
       }
     }
   }
   return num_valid_regions;
 }
 
 }  // namespace
 
 // static
-ProcessMemoryMapsDumpProvider* ProcessMemoryMapsDumpProvider::GetInstance() {
-  return Singleton<ProcessMemoryMapsDumpProvider,
-                   LeakySingletonTraits<ProcessMemoryMapsDumpProvider>>::get();
+scoped_ptr<ProcessMemoryMapsDumpProvider>
+ProcessMemoryMapsDumpProvider::CreateForProcess(ProcessHandle process) {
+  return make_scoped_ptr(new ProcessMemoryMapsDumpProvider(process));
 }
 
-ProcessMemoryMapsDumpProvider::ProcessMemoryMapsDumpProvider() {
-}
+ProcessMemoryMapsDumpProvider::ProcessMemoryMapsDumpProvider(
+    ProcessHandle process)
+    : process_(process) {}
 
 ProcessMemoryMapsDumpProvider::~ProcessMemoryMapsDumpProvider() {
 }
 
 // Called at trace dump point time. Creates a snapshot of the memory maps for
 // the current process.
 bool ProcessMemoryMapsDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,
                                                  ProcessMemoryDump* pmd) {
   // Snapshot of memory maps is not taken for light dump requests.
   if (args.level_of_detail == MemoryDumpLevelOfDetail::LIGHT)
     return true;
 
   uint32 res = 0;
   if (UNLIKELY(proc_smaps_for_testing)) {
     res = ReadLinuxProcSmapsFile(proc_smaps_for_testing, pmd->process_mmaps());
   } else {
     ScopedFILE smaps_file(fopen("/proc/self/smaps", "r"));
     res = ReadLinuxProcSmapsFile(smaps_file.get(), pmd->process_mmaps());
   }
 
   if (res > 0) {
     pmd->set_has_process_mmaps();
     return true;
   }
   return false;
 }
 
 }  // namespace trace_event
 }  // namespace base