Same origin preconnects: Make retry delay a finch configurable param

This allows us to experiment with larger values for retry delay
(e.g., value of 5 seconds would ensure that most of the preconnects
finish by that time). Larger values would result in subsequent
preconnects being not no-op.

Change-Id: I0f35fce774ee752ede434806e7b23f3d1b724e4e
Bug: 1130607
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2419556Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808971}

chrome/browser/navigation_predictor/navigation_predictor_features.cc

@@ -24,4 +24,9 @@ const base::Feature
         "NavigationPredictorEnablePreconnectOnSameDocumentNavigations",
         base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Used for controlling the navigation predictor based preconnect experiments.
+const base::Feature kNavigationPredictorPreconnectSocketCompletionTime{
+    "NavigationPredictorPreconnectSocketCompletionTime",
+    base::FEATURE_DISABLED_BY_DEFAULT};
+
 }  // namespace features

chrome/browser/navigation_predictor/navigation_predictor_features.h

@@ -14,6 +14,7 @@ namespace features {
 extern const base::Feature kNavigationPredictorPreconnectHoldback;
 extern const base::Feature
     kNavigationPredictorEnablePreconnectOnSameDocumentNavigations;
+extern const base::Feature kNavigationPredictorPreconnectSocketCompletionTime;
 
 }  // namespace features
 

chrome/browser/navigation_predictor/navigation_predictor_preconnect_client.cc

@@ -179,7 +179,10 @@ void NavigationPredictorPreconnectClient::MaybePreconnectNow(
 
   // The delay beyond the idle socket timeout that net uses when
   // re-preconnecting. If negative, no retries occur.
-  constexpr int retry_delay_ms = 50;
+  const base::TimeDelta retry_delay =
+      base::TimeDelta::FromMilliseconds(base::GetFieldTrialParamByFeatureAsInt(
+          features::kNavigationPredictorPreconnectSocketCompletionTime,
+          "preconnect_socket_completion_time_msec", 50));
 
   // Set/Reset the timer to fire after the preconnect times out. Add an extra
   // delay to make sure the preconnect has expired if it wasn't used.
@@ -187,8 +190,8 @@ void NavigationPredictorPreconnectClient::MaybePreconnectNow(
       FROM_HERE,
       base::TimeDelta::FromSeconds(base::GetFieldTrialParamByFeatureAsInt(
           net::features::kNetUnusedIdleSocketTimeout,
-          "unused_idle_socket_timeout_seconds", 10)) +
-          base::TimeDelta::FromMilliseconds(retry_delay_ms),
+          "unused_idle_socket_timeout_seconds", 60)) +
+          retry_delay,
       base::BindOnce(&NavigationPredictorPreconnectClient::MaybePreconnectNow,
                      base::Unretained(this), preconnects_attempted + 1));
 }

chrome/browser/navigation_predictor/search_engine_preconnector.cc

@@ -8,6 +8,7 @@
 #include "base/metrics/field_trial_params.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "chrome/browser/navigation_predictor/navigation_predictor_features.h"
 #include "chrome/browser/predictors/loading_predictor.h"
 #include "chrome/browser/predictors/loading_predictor_factory.h"
 #include "chrome/browser/profiles/profile.h"
@@ -106,7 +107,10 @@ void SearchEnginePreconnector::PreconnectDSE() {
 
   // The delay beyond the idle socket timeout that net uses when
   // re-preconnecting. If negative, no retries occur.
-  constexpr base::TimeDelta kRelayDelay = base::TimeDelta::FromMilliseconds(50);
+  const base::TimeDelta retry_delay =
+      base::TimeDelta::FromMilliseconds(base::GetFieldTrialParamByFeatureAsInt(
+          features::kNavigationPredictorPreconnectSocketCompletionTime,
+          "preconnect_socket_completion_time_msec", 50));
 
   // Set/Reset the timer to fire after the preconnect times out. Add an extra
   // delay to make sure the preconnect has expired if it wasn't used.
@@ -115,7 +119,7 @@ void SearchEnginePreconnector::PreconnectDSE() {
       base::TimeDelta::FromSeconds(base::GetFieldTrialParamByFeatureAsInt(
           net::features::kNetUnusedIdleSocketTimeout,
           "unused_idle_socket_timeout_seconds", 60)) +
-          kRelayDelay,
+          retry_delay,
       base::BindOnce(&SearchEnginePreconnector::PreconnectDSE,
                      base::Unretained(this)));
 }