Add Startup.BrowserView.FirstPaint / .CompositingEnded histograms.

components/startup_metric_utils/browser/startup_metric_utils.cc

 // Copyright 2013 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.
 
 #include "components/startup_metric_utils/browser/startup_metric_utils.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
@@ skipping 751 matching lines @@
     return;
 
   base::StackSamplingProfiler::SetProcessMilestone(
       metrics::CallStackProfileMetricsProvider::MAIN_NAVIGATION_FINISHED);
   UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE_AND_SAME_VERSION_COUNT(
       UMA_HISTOGRAM_LONG_TIMES_100,
       "Startup.FirstWebContents.MainNavigationFinished",
       g_process_creation_ticks.Get(), ticks);
 }
 
+void RecordBrowserViewFirstPaint(const base::TimeTicks& ticks) {
+  static bool is_first_call = true;
+  if (!is_first_call || ticks.is_null())
+    return;
+  is_first_call = false;
+
+  UMA_HISTOGRAM_WITH_TEMPERATURE(UMA_HISTOGRAM_LONG_TIMES_100,

[gab, 2017/04/04 20:44:21]

UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE for this one too

[themblsha, 2017/04/05 13:20:08]

Done.

+                                 "Startup.BrowserView.FirstPaint",
+                                 ticks - g_process_creation_ticks.Get());
+}
+
+void RecordBrowserViewFirstPaintCompositingEnded(const base::TimeTicks& ticks) {
+  static bool is_first_call = true;
+  if (!is_first_call || ticks.is_null())
+    return;
+  is_first_call = false;
+
+  UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE(
+      UMA_HISTOGRAM_LONG_TIMES_100,
+      "Startup.BrowserView.FirstPaint.CompositingEnded",
+      g_process_creation_ticks.Get(), ticks);
+}
+
 base::TimeTicks MainEntryPointTicks() {
   return g_browser_main_entry_point_ticks.Get();
 }
 
 }  // namespace startup_metric_utils