From 8597dad96e12029f5afc4fda445149133a6fc3f9 Mon Sep 17 00:00:00 2001
From: Luna Lu <loonybear@chromium.org>
Date: Thu, 31 May 2018 15:28:28 +0000
Subject: [PATCH] client side changes to run a field trial for page load
 metrics sender

Bug: 847269
Change-Id: I9303c0cb0f770d61b25532b8f32d6b8edcd09731
Reviewed-on: https://chromium-review.googlesource.com/1075555
Commit-Queue: Luna Lu <loonybear@chromium.org>
Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#562475}(cherry picked from commit 188a49e42f794472140da7636f3d779a26955c7b)
Reviewed-on: https://chromium-review.googlesource.com/1079735
Reviewed-by: Luna Lu <loonybear@chromium.org>
Cr-Commit-Position: refs/branch-heads/3440@{#60}
Cr-Branched-From: 010ddcfda246975d194964ccf20038ebbdec6084-refs/heads/master@{#561733}
---
 .../page_load_metrics/page_timing_metrics_sender.cc  | 12 ++++++++++--
 .../page_load_metrics/page_timing_metrics_sender.h   |  4 ++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/chrome/renderer/page_load_metrics/page_timing_metrics_sender.cc b/chrome/renderer/page_load_metrics/page_timing_metrics_sender.cc
index 9337c26d7eb3..ce4b02a62df3 100644
--- a/chrome/renderer/page_load_metrics/page_timing_metrics_sender.cc
+++ b/chrome/renderer/page_load_metrics/page_timing_metrics_sender.cc
@@ -7,6 +7,8 @@
 #include <utility>
 
 #include "base/callback.h"
+#include "base/feature_list.h"
+#include "base/metrics/field_trial_params.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "chrome/common/page_load_metrics/page_load_metrics_constants.h"
@@ -16,6 +18,8 @@ namespace page_load_metrics {
 
 namespace {
 const int kInitialTimerDelayMillis = 50;
+const base::Feature kPageLoadMetricsTimerDelayFeature{
+    "PageLoadMetricsTimerDelay", base::FEATURE_DISABLED_BY_DEFAULT};
 }  // namespace
 
 PageTimingMetricsSender::PageTimingMetricsSender(
@@ -26,7 +30,11 @@ PageTimingMetricsSender::PageTimingMetricsSender(
       timer_(std::move(timer)),
       last_timing_(std::move(initial_timing)),
       metadata_(mojom::PageLoadMetadata::New()),
-      new_features_(mojom::PageLoadFeatures::New()) {
+      new_features_(mojom::PageLoadFeatures::New()),
+      buffer_timer_delay_ms_(kBufferTimerDelayMillis) {
+  buffer_timer_delay_ms_ = base::GetFieldTrialParamByFeatureAsInt(
+      kPageLoadMetricsTimerDelayFeature, "BufferTimerDelayMillis",
+      kBufferTimerDelayMillis /* default value */);
   if (!IsEmpty(*last_timing_)) {
     EnsureSendTimer();
   }
@@ -93,7 +101,7 @@ void PageTimingMetricsSender::EnsureSendTimer() {
     // Send the first IPC eagerly to make sure the receiving side knows we're
     // sending metrics as soon as possible.
     int delay_ms =
-        have_sent_ipc_ ? kBufferTimerDelayMillis : kInitialTimerDelayMillis;
+        have_sent_ipc_ ? buffer_timer_delay_ms_ : kInitialTimerDelayMillis;
     timer_->Start(
         FROM_HERE, base::TimeDelta::FromMilliseconds(delay_ms),
         base::Bind(&PageTimingMetricsSender::SendNow, base::Unretained(this)));
diff --git a/chrome/renderer/page_load_metrics/page_timing_metrics_sender.h b/chrome/renderer/page_load_metrics/page_timing_metrics_sender.h
index 427392f2d35b..730e3e3def8a 100644
--- a/chrome/renderer/page_load_metrics/page_timing_metrics_sender.h
+++ b/chrome/renderer/page_load_metrics/page_timing_metrics_sender.h
@@ -64,6 +64,10 @@ class PageTimingMetricsSender {
 
   bool have_sent_ipc_ = false;
 
+  // Field trial for alternating page timing metrics sender buffer timer delay.
+  // https://crbug.com/847269.
+  int buffer_timer_delay_ms_;
+
   DISALLOW_COPY_AND_ASSIGN(PageTimingMetricsSender);
 };