Refactor recording of the Startup.FirstWebContents.RenderProcessHostInit.ToNonEmptyPaint metric

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 29 matching lines @@
 // Mark as volatile to defensively make sure usage is thread-safe.
 // Note that at the time of this writing, access is only on the UI thread.
 volatile bool g_main_window_startup_interrupted = false;
 
 base::LazyInstance<base::TimeTicks>::Leaky g_process_creation_ticks =
     LAZY_INSTANCE_INITIALIZER;
 
 base::LazyInstance<base::TimeTicks>::Leaky g_browser_main_entry_point_ticks =
     LAZY_INSTANCE_INITIALIZER;
 
+base::LazyInstance<base::TimeTicks>::Leaky
+    g_first_render_process_host_init_ticks = LAZY_INSTANCE_INITIALIZER;
+
 base::LazyInstance<base::TimeTicks>::Leaky g_renderer_main_entry_point_ticks =
     LAZY_INSTANCE_INITIALIZER;
 
 base::LazyInstance<base::TimeTicks>::Leaky
     g_browser_exe_main_entry_point_ticks = LAZY_INSTANCE_INITIALIZER;
 
 base::LazyInstance<base::TimeTicks>::Leaky g_message_loop_start_ticks =
     LAZY_INSTANCE_INITIALIZER;
 
 // Only used by RecordMainEntryTimeHistogram(), should go away with it (do not
@@ skipping 631 matching lines @@
 void RecordBrowserOpenTabsDelta(base::TimeDelta delta) {
   static bool is_first_call = true;
   if (!is_first_call)
     return;
   is_first_call = false;
 
   UMA_HISTOGRAM_WITH_TEMPERATURE_AND_SAME_VERSION_COUNT(
       UMA_HISTOGRAM_LONG_TIMES_100, "Startup.BrowserOpenTabs", delta);
 }
 
+void RecordFirstRenderProcessHostInit(base::TimeTicks ticks) {
+  if (g_first_render_process_host_init_ticks.Get().is_null())
+    g_first_render_process_host_init_ticks.Get() = ticks;
+}
+
 void RecordRendererMainEntryTime(base::TimeTicks ticks) {
   // Record the renderer main entry time, but don't log the UMA metric
   // immediately because the startup temperature is not known yet.
   if (g_renderer_main_entry_point_ticks.Get().is_null())
     g_renderer_main_entry_point_ticks.Get() = ticks;
 }
 
 void RecordFirstWebContentsMainFrameLoad(base::TimeTicks ticks) {
   static bool is_first_call = true;
   if (!is_first_call || ticks.is_null())
     return;
   is_first_call = false;
   if (!ShouldLogStartupHistogram())
     return;
 
   UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE_AND_SAME_VERSION_COUNT(
       UMA_HISTOGRAM_LONG_TIMES_100, "Startup.FirstWebContents.MainFrameLoad2",
       g_process_creation_ticks.Get(), ticks);
 }
 
-void RecordFirstWebContentsNonEmptyPaint(
-    base::TimeTicks now,
-    base::TimeTicks render_process_host_init_time) {
+void RecordFirstWebContentsNonEmptyPaint(base::TimeTicks ticks) {
   static bool is_first_call = true;
-  if (!is_first_call || now.is_null())
+  if (!is_first_call || ticks.is_null())
     return;
   is_first_call = false;
 
   // Log Startup.BrowserMainToRendererMain now that the first renderer main
   // entry time and the startup temperature are known.
   RecordRendererMainEntryHistogram();
 
   if (!ShouldLogStartupHistogram())
     return;
 
   base::StackSamplingProfiler::SetProcessMilestone(
       metrics::CallStackProfileMetricsProvider::FIRST_NONEMPTY_PAINT);
   UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE_AND_SAME_VERSION_COUNT(
       UMA_HISTOGRAM_LONG_TIMES_100, "Startup.FirstWebContents.NonEmptyPaint2",
-      g_process_creation_ticks.Get(), now);
+      g_process_creation_ticks.Get(), ticks);
   UMA_HISTOGRAM_WITH_TEMPERATURE(
       UMA_HISTOGRAM_LONG_TIMES_100,
       "Startup.BrowserMessageLoopStart.To.NonEmptyPaint2",
-      now - g_message_loop_start_ticks.Get());
+      ticks - g_message_loop_start_ticks.Get());
 
-  UMA_HISTOGRAM_WITH_TEMPERATURE(
+  UMA_HISTOGRAM_AND_TRACE_WITH_TEMPERATURE_AND_SAME_VERSION_COUNT(

[gab, 2017/06/02 18:31:33]

Let's not bother with "AND_SAME_VERSION_COUNT" (we should drop that suffix, no
one looks at it anymore IMO)

       UMA_HISTOGRAM_LONG_TIMES_100,
       "Startup.FirstWebContents.RenderProcessHostInit.ToNonEmptyPaint",
-      now - render_process_host_init_time);
+      g_first_render_process_host_init_ticks.Get(), ticks);
 }
 
 void RecordFirstWebContentsMainNavigationStart(base::TimeTicks ticks,
                                                WebContentsWorkload workload) {
   static bool is_first_call = true;
   if (!is_first_call || ticks.is_null())
     return;
   is_first_call = false;
   if (!ShouldLogStartupHistogram())
     return;
@@ skipping 67 matching lines @@
       UMA_HISTOGRAM_LONG_TIMES_100,
       "Startup.BrowserWindow.FirstPaint.CompositingEnded",
       g_process_creation_ticks.Get(), ticks);
 }
 
 base::TimeTicks MainEntryPointTicks() {
   return g_browser_main_entry_point_ticks.Get();
 }
 
 }  // namespace startup_metric_utils