Remove net.http_server_properties entry from profile prefs file.

I migrated it to the network service's pref files a year or so back,
but didn't realize unregistered prefs weren't automatically pruned from
preference files, so never deleted the old entries. Given that this pref
can be quite large, it definitely needs to be pruned.

Bug: 715695
Change-Id: Ia9f1592a5064cdcdfe22bf144c5c5e66a272ec9d
Reviewed-on: https://chromium-review.googlesource.com/c/1344989
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609817}

chrome/browser/prefs/browser_prefs.cc

@@ -382,6 +382,9 @@ const char kReverseAutologinEnabled[] = "reverse_autologin.enabled";
 const char kNetworkQualities[] = "net.network_qualities";
 const char kForceSessionSync[] = "settings.history_recorded";
 const char kOnboardDuringNUX[] = "browser.onboard_during_nux";
+// This pref is particularly large, taking up 15+% of the prefs file, so should
+// perhaps be kept around longer than the others.
+const char kHttpServerProperties[] = "net.http_server_properties";
 
 // Register prefs used only for migration (clearing or moving to a new key).
 void RegisterProfilePrefsForMigration(
@@ -412,6 +415,8 @@ void RegisterProfilePrefsForMigration(
   registry->RegisterDictionaryPref(kNetworkQualities, PrefRegistry::LOSSY_PREF);
   registry->RegisterBooleanPref(kForceSessionSync, false);
   registry->RegisterBooleanPref(kOnboardDuringNUX, false);
+  registry->RegisterDictionaryPref(kHttpServerProperties,
+                                   PrefRegistry::LOSSY_PREF);
 }
 
 }  // namespace
@@ -876,4 +881,5 @@ void MigrateObsoleteProfilePrefs(Profile* profile) {
   profile_prefs->ClearPref(kNetworkQualities);
   profile_prefs->ClearPref(kForceSessionSync);
   profile_prefs->ClearPref(kOnboardDuringNUX);
+  profile_prefs->ClearPref(kHttpServerProperties);
 }