Add support for single sample metrics.

components/metrics/BUILD.gn

 # Copyright 2014 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.
 
 import("//testing/test.gni")
 
 static_library("metrics") {
   sources = [
     "call_stack_profile_metrics_provider.cc",
     "call_stack_profile_metrics_provider.h",
@@ skipping 77 matching lines @@
     "system_memory_stats_recorder_win.cc",
     "url_constants.cc",
     "url_constants.h",
   ]
 
   public_deps = [
     "//components/metrics/proto",
   ]
   deps = [
     ":call_stack_profile_params",
+    ":single_value_histograms",
     "//base",
     "//base:base_static",
     "//components/browser_watcher:stability",
     "//components/browser_watcher:stability_data",
     "//components/prefs",
     "//components/variations",
     "//third_party/zlib:compression_utils",
   ]
 
   if (is_chromeos) {
@@ skipping 133 matching lines @@
 
     public_deps = [
       ":profiler",
     ]
     deps = [
       "//base",
     ]
   }
 }
 
+source_set("single_value_histograms") {
+  sources = [
+    "single_value_counts_histogram.cc",
+    "single_value_counts_histogram.h",
+    "single_value_histograms_factory_impl.cc",
+    "single_value_histograms_factory_impl.h",
+    "single_value_histograms_provider.cc",
+    "single_value_histograms_provider.h",
+  ]
+
+  deps = [
+    "//components/metrics/public/interfaces:single_value_histograms_mojo_bindings",
+    "//mojo/public/cpp/bindings",
+  ]
+}
+
 source_set("call_stack_profile_params") {
   sources = [
     "call_stack_profile_params.cc",
     "call_stack_profile_params.h",
   ]
 }
 
 source_set("call_stacks") {
   sources = [
     "call_stack_profile_collector.cc",
@@ skipping 122 matching lines @@
 # Convenience testing target
 test("metrics_unittests") {
   sources = [
     "//components/test/run_all_unittests.cc",
   ]
   deps = [
     ":unit_tests",
     "//components/test:test_support",
   ]
 }