Do not persist HttpServerProperties to disk that often.

net/http/http_server_properties_manager.cc

Index: net/http/http_server_properties_manager.cc
diff --git a/net/http/http_server_properties_manager.cc b/net/http/http_server_properties_manager.cc
index 467c5b804545251f3a0dfde3271165d2be0c2e18..75862b2b2393abb352a197dacfba7b5e0edeb5cd 100644
--- a/net/http/http_server_properties_manager.cc
+++ b/net/http/http_server_properties_manager.cc
@@ -25,12 +25,16 @@ namespace {
 // Time to wait before starting an update the http_server_properties_impl_ cache
 // from preferences. Scheduling another update during this period will reset the
 // timer.
-const int64_t kUpdateCacheDelayMs = 1000;
+const int64_t kUpdateCacheDelayMs = 1000;  // 1 second
 
 // Time to wait before starting an update the preferences from the
 // http_server_properties_impl_ cache. Scheduling another update during this
 // period will reset the timer.
-const int64_t kUpdatePrefsDelayMs = 60000;
+const int64_t kUpdatePrefsDelayMs = 60000;  // 1 minute
+
+// Maximum time to wait between ScheduleUpdatePrefsOnNetworkThread() calls from
+// SetAlternativeService() and SetAlternativeServices().
+const int64_t kAlternativeServicesUpdatePrefsMs = 300000;  // 5 minutes
 
 // "version" 0 indicates, http_server_properties doesn't have "version"
 // property.
@@ -81,7 +85,10 @@ HttpServerPropertiesManager::HttpServerPropertiesManager(
     : pref_task_runner_(base::ThreadTaskRunnerHandle::Get()),
       pref_delegate_(pref_delegate),
       setting_prefs_(false),
-      network_task_runner_(network_task_runner) {
+      network_task_runner_(network_task_runner),
+      last_update_prefs_from_cache_(
+          base::Time::Now() -
+          base::TimeDelta::FromSeconds(kAlternativeServicesUpdatePrefsMs)) {

[Ryan Hamilton, 2016/07/22 23:31:35]

Should this be "FromMilliseconds()"? (Here and elsewhere)

   DCHECK(pref_delegate_);
   pref_weak_ptr_factory_.reset(
       new base::WeakPtrFactory<HttpServerPropertiesManager>(this));
@@ -195,8 +202,12 @@ bool HttpServerPropertiesManager::SetAlternativeService(
     const AlternativeService& alternative_service,
     base::Time expiration) {
   DCHECK(network_task_runner_->RunsTasksOnCurrentThread());
-  const bool changed = http_server_properties_impl_->SetAlternativeService(
-      origin, alternative_service, expiration);
+  const bool changed =
+      http_server_properties_impl_->SetAlternativeService(
+          origin, alternative_service, expiration) ||
+      (last_update_prefs_from_cache_ +
+           base::TimeDelta::FromSeconds(kAlternativeServicesUpdatePrefsMs) <
+       base::Time::Now());
   if (changed) {
     ScheduleUpdatePrefsOnNetworkThread(SET_ALTERNATIVE_SERVICES);
   }
@@ -207,8 +218,12 @@ bool HttpServerPropertiesManager::SetAlternativeServices(
     const url::SchemeHostPort& origin,
     const AlternativeServiceInfoVector& alternative_service_info_vector) {
   DCHECK(network_task_runner_->RunsTasksOnCurrentThread());
-  const bool changed = http_server_properties_impl_->SetAlternativeServices(
-      origin, alternative_service_info_vector);
+  const bool changed =
+      http_server_properties_impl_->SetAlternativeServices(
+          origin, alternative_service_info_vector) ||
+      (last_update_prefs_from_cache_ +
+           base::TimeDelta::FromSeconds(kAlternativeServicesUpdatePrefsMs) <
+       base::Time::Now());
   if (changed) {
     ScheduleUpdatePrefsOnNetworkThread(SET_ALTERNATIVE_SERVICES);
   }
@@ -896,6 +911,7 @@ void HttpServerPropertiesManager::UpdatePrefsFromCacheOnNetworkThread() {
 void HttpServerPropertiesManager::UpdatePrefsFromCacheOnNetworkThread(
     const base::Closure& completion) {
   DCHECK(network_task_runner_->RunsTasksOnCurrentThread());
+  last_update_prefs_from_cache_ = base::Time::Now();
 
   // It is in MRU order.
   base::ListValue* spdy_server_list = new base::ListValue;