Add Startup.BrowserView.FirstPaint / .CompositingEnded histograms.

components/startup_metric_utils/browser/startup_metric_utils.cc

Index: components/startup_metric_utils/browser/startup_metric_utils.cc
diff --git a/components/startup_metric_utils/browser/startup_metric_utils.cc b/components/startup_metric_utils/browser/startup_metric_utils.cc
index f1ad613d5df94bc95887beaafc255f963664c4c6..e1469d4d1b813d956824b10d5ade3ac1aac1f582 100644
--- a/components/startup_metric_utils/browser/startup_metric_utils.cc
+++ b/components/startup_metric_utils/browser/startup_metric_utils.cc
@@ -769,6 +769,29 @@ void RecordFirstWebContentsMainNavigationFinished(
       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();
 }