memory-infra: Add peak-detector skeleton.

base/trace_event/memory_dump_manager_unittest.cc

Index: base/trace_event/memory_dump_manager_unittest.cc
diff --git a/base/trace_event/memory_dump_manager_unittest.cc b/base/trace_event/memory_dump_manager_unittest.cc
index 86c90d43f05261aa90f97e2eebb4fb2316cd37db..faae270ee1881b6ab823834b4e88a8681df4a831 100644
--- a/base/trace_event/memory_dump_manager_unittest.cc
+++ b/base/trace_event/memory_dump_manager_unittest.cc
@@ -116,8 +116,6 @@ void PostTaskAndWait(const tracked_objects::Location& from_here,
   event.Wait();
 }
 
-}  // namespace
-
 // Testing MemoryDumpManagerDelegate which, by default, short-circuits dump
 // requests locally to the MemoryDumpManager instead of performing IPC dances.
 class MemoryDumpManagerDelegateForTesting : public MemoryDumpManagerDelegate {
@@ -214,6 +212,8 @@ class TestSequencedTaskRunner : public SequencedTaskRunner {
   unsigned num_of_post_tasks_;
 };
 
+}  // namespace
+
 class MemoryDumpManagerTest : public testing::Test {
  public:
   MemoryDumpManagerTest() : testing::Test(), kDefaultOptions() {}