[tracing] Move GN/gyp build files under trace_event

base/trace_event/BUILD.gn

Index: base/trace_event/BUILD.gn
diff --git a/base/trace_event/BUILD.gn b/base/trace_event/BUILD.gn
index aec694aa5db0891d69699e89beb776fd831de051..479a918484322712ffaef6d261584225418a7c93 100644
--- a/base/trace_event/BUILD.gn
+++ b/base/trace_event/BUILD.gn
@@ -1,4 +1,4 @@
-# Copyright (c) 2015 The Chromium Authors. All rights reserved.
+# 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.
 
@@ -63,3 +63,25 @@ source_set("trace_event") {
 
   visibility = [ "//base/*" ]
 }
+
+source_set("trace_event_unittests") {
+  testonly = true
+  sources = [
+    "memory_allocator_dump_unittest.cc",
+    "memory_dump_manager_unittest.cc",
+    "process_memory_maps_dump_provider_unittest.cc",
+    "process_memory_totals_dump_provider_unittest.cc",
+    "trace_event_argument_unittest.cc",
+    "trace_event_memory_unittest.cc",
+    "trace_event_synthetic_delay_unittest.cc",
+    "trace_event_system_stats_monitor_unittest.cc",
+    "trace_event_unittest.cc",
+    "trace_event_win_unittest.cc",
+  ]
+
+  deps = [
+    "//base/test:test_support",
+    "//testing/gmock",
+    "//testing/gtest",
+  ]
+}