Add leakDetectionMetric for tracing

tracing/trace_viewer.gypi

 # Copyright (c) 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.
 
 {
   'variables': {
     'tracing_css_files': [
       'tracing/ui/base/list_view.css',
       'tracing/ui/extras/about_tracing/common.css',
       'tracing/ui/extras/chrome/cc/display_item_list_view.css',
@@ skipping 175 matching lines @@
       'tracing/importer/find_startup_expectations.html',
       'tracing/importer/import.html',
       'tracing/importer/importer.html',
       'tracing/importer/proto_expectation.html',
       'tracing/importer/simple_line_reader.html',
       'tracing/importer/user_model_builder.html',
       'tracing/metrics/all_fixed_color_schemes.html',
       'tracing/metrics/all_metrics.html',
       'tracing/metrics/android_systrace_metric.html',
       'tracing/metrics/blink/gc_metric.html',
+      'tracing/metrics/blink/leak_detection_metric.html',
       'tracing/metrics/cpu_process_metric.html',
       'tracing/metrics/media_metric.html',
       'tracing/metrics/metric_map_function.html',
       'tracing/metrics/metric_registry.html',
       'tracing/metrics/sample_metric.html',
       'tracing/metrics/spa_navigation_helper.html',
       'tracing/metrics/spa_navigation_metric.html',
       'tracing/metrics/system_health/breakdown_tree_helpers.html',
       'tracing/metrics/system_health/clock_sync_latency_metric.html',
       'tracing/metrics/system_health/cpu_time_metric.html',
@@ skipping 379 matching lines @@
       'tracing/ui/images/chrome-right.png',
       'tracing/ui/images/ui-states.png',
     ],
     'tracing_files': [
       '<@(tracing_css_files)',
       '<@(tracing_js_html_files)',
       '<@(tracing_img_files)',
     ],
   }
 }