Move Singleton and related structs to namespace base

base/trace_event/winheap_dump_provider_win.cc

Index: base/trace_event/winheap_dump_provider_win.cc
diff --git a/base/trace_event/winheap_dump_provider_win.cc b/base/trace_event/winheap_dump_provider_win.cc
index 8f910b3ce15d69bc797e992ffc148b453b9d3561..b9a729202c8813a4e34825fa1872c1c00ae00eb6 100644
--- a/base/trace_event/winheap_dump_provider_win.cc
+++ b/base/trace_event/winheap_dump_provider_win.cc
@@ -43,8 +43,8 @@ void ReportHeapDump(ProcessMemoryDump* pmd, const WinHeapInfo& heap_info) {
 }  // namespace
 
 WinHeapDumpProvider* WinHeapDumpProvider::GetInstance() {
-  return Singleton<WinHeapDumpProvider,
-                   LeakySingletonTraits<WinHeapDumpProvider>>::get();
+  return base::Singleton<WinHeapDumpProvider,
+                   base::LeakySingletonTraits<WinHeapDumpProvider>>::get();
 }
 
 bool WinHeapDumpProvider::OnMemoryDump(const MemoryDumpArgs& args,