metrics: Add leak detector controller in Chrome OS metrics system

components/metrics/BUILD.gn

Index: components/metrics/BUILD.gn
diff --git a/components/metrics/BUILD.gn b/components/metrics/BUILD.gn
index 13701ba3e2b6489746c7c90fbf3be3c66e66ea09..56ef4afe176e85fd97c52891e49ea99d79c6c90b 100644
--- a/components/metrics/BUILD.gn
+++ b/components/metrics/BUILD.gn
@@ -2,6 +2,18 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/buildflag_header.gni")
+import("//components/metrics/leak_detector/leak_detector.gni")
+
+buildflag_header("metrics_flags") {
+  header = "metrics_flags.h"
+
+  flags = [
+    # Enable runtime leak detector.
+    "ENABLE_LEAK_DETECTOR=$enable_leak_detector",
+  ]
+}
+
 # GYP version: components/metrics.gypi:metrics
 source_set("metrics") {
   sources = [
@@ -61,6 +73,7 @@ source_set("metrics") {
   ]
 
   public_deps = [
+    ":metrics_flags",
     "//components/metrics/proto",
   ]
   deps = [
@@ -121,6 +134,8 @@ if (is_chromeos) {
       "leak_detector/custom_allocator.h",
       "leak_detector/leak_analyzer.cc",
       "leak_detector/leak_analyzer.h",
+      "leak_detector/leak_detector.cc",
+      "leak_detector/leak_detector.h",
       "leak_detector/leak_detector_impl.cc",
       "leak_detector/leak_detector_impl.h",
       "leak_detector/leak_detector_value_type.cc",
@@ -283,6 +298,7 @@ if (is_chromeos) {
       "leak_detector/call_stack_table_unittest.cc",
       "leak_detector/leak_analyzer_unittest.cc",
       "leak_detector/leak_detector_impl_unittest.cc",
+      "leak_detector/leak_detector_unittest.cc",
       "leak_detector/ranked_list_unittest.cc",
     ]