Clean up SqlSkipPreload feature.

Bug: 1126640
Change-Id: I87de57b6c22c6b2f7bda8c6ca6a8b501436f863b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2435327Reviewed-by: Victor Costan <pwnall@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#812006}

sql/database.cc

@@ -360,8 +360,6 @@ void Database::Close() {
 
 void Database::Preload() {
   TRACE_EVENT0("sql", "Database::Preload");
-  if (base::FeatureList::IsEnabled(features::kSqlSkipPreload))
-    return;
 
   if (!db_) {
     DCHECK(poisoned_) << "Cannot preload null db";

sql/sql_features.cc

@@ -8,18 +8,6 @@ namespace sql {
 
 namespace features {
 
-// Skip the logic for preloading databases.
-//
-// Enabling this feature turns sql::Database::Preload() into a noop.
-// https://crbug.com/243949 suggests that sql::Database::Preload() was added
-// without any proper benchmarking, and the logic is a pessimization for modern
-// OS schedulers.
-//
-// TODO(pwnall): After the performance impact of the change is assessed, remove
-//               sql::Database::Preload() and this flag.
-const base::Feature kSqlSkipPreload{"SqlSkipPreload",
-                                    base::FEATURE_DISABLED_BY_DEFAULT};
-
 // Enable WAL mode for all SQLite databases.
 const base::Feature kEnableWALModeByDefault{"EnableWALModeByDefault",
                                             base::FEATURE_DISABLED_BY_DEFAULT};

sql/sql_features.h

@@ -12,8 +12,6 @@ namespace sql {
 
 namespace features {
 
-COMPONENT_EXPORT(SQL) extern const base::Feature kSqlSkipPreload;
-
 COMPONENT_EXPORT(SQL) extern const base::Feature kEnableWALModeByDefault;
 
 }  // namespace features

testing/variations/fieldtrial_testing_config.json

@@ -6440,27 +6440,6 @@
             ]
         }
     ],
-    "SqlSkipPreload": [
-        {
-            "platforms": [
-                "android",
-                "android_weblayer",
-                "chromeos",
-                "linux",
-                "mac",
-                "ios",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "SqlSkipPreload"
-                    ]
-                }
-            ]
-        }
-    ],
     "StorageServiceOutOfProcess": [
         {
             "platforms": [