Enable SimpleCachePrioritizedCaching feature by default

We don't see any significant impact on Chrome UMA [1]. But, we did see a
significant positive impact on the server side metrics [2].
So I’d like to enable the SimpleCachePrioritizedCaching feature.

[1]: http://shortn/_p3umbfyPGw
[2]: http://shortn/_KA6W8hLpgK

Bug: 380957432
Change-Id: Ib4a4fa423f430a0e1037415a00ba9fb5e7d31c7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6267559
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1421017}

net/base/features.cc

@@ -651,7 +651,7 @@ BASE_FEATURE(kIgnoreHSTSForLocalhost,
 
 BASE_FEATURE(kSimpleCachePrioritizedCaching,
              "SimpleCachePrioritizedCaching",
-             base::FEATURE_DISABLED_BY_DEFAULT);
+             base::FEATURE_ENABLED_BY_DEFAULT);
 
 const base::FeatureParam<int>
     kSimpleCachePrioritizedCachingPrioritizationFactor{

net/disk_cache/simple/simple_index_unittest.cc

@@ -679,19 +679,7 @@ TEST_F(SimpleIndexTest, EvictBySize2) {
   ASSERT_EQ(2u, last_doom_entry_hashes().size());
 }
 
-class SimpleIndexPrioritizedCachingTest : public SimpleIndexTest {
- public:
-  SimpleIndexPrioritizedCachingTest() {
-    feature_list_.InitAndEnableFeature(
-        net::features::kSimpleCachePrioritizedCaching);
-  }
-  ~SimpleIndexPrioritizedCachingTest() override = default;
-
- private:
-  base::test::ScopedFeatureList feature_list_;
-};
-
-TEST_F(SimpleIndexPrioritizedCachingTest, EvictPrioritization) {
+TEST_F(SimpleIndexTest, EvictPrioritization) {
   const auto caching_prioritization_period =
       net::features::kSimpleCachePrioritizedCachingPrioritizationPeriod.Get();
   auto now = base::Time::Now();
@@ -723,7 +711,7 @@ TEST_F(SimpleIndexPrioritizedCachingTest, EvictPrioritization) {
   ASSERT_EQ(1u, last_doom_entry_hashes().size());
 }
 
-TEST_F(SimpleIndexPrioritizedCachingTest, EvictPrioritizationOutOfPeriod) {
+TEST_F(SimpleIndexTest, EvictPrioritizationOutOfPeriod) {
   const auto caching_prioritization_period =
       net::features::kSimpleCachePrioritizedCachingPrioritizationPeriod.Get();
   auto now = base::Time::Now();
@@ -755,7 +743,20 @@ TEST_F(SimpleIndexPrioritizedCachingTest, EvictPrioritizationOutOfPeriod) {
   ASSERT_EQ(1u, last_doom_entry_hashes().size());
 }
 
-TEST_F(SimpleIndexTest, EvictPrioritizationFeatureDefaultDisabled) {
+class SimpleIndexPrioritizedCachingDisabledTest : public SimpleIndexTest {
+ public:
+  SimpleIndexPrioritizedCachingDisabledTest() {
+    feature_list_.InitAndDisableFeature(
+        net::features::kSimpleCachePrioritizedCaching);
+  }
+  ~SimpleIndexPrioritizedCachingDisabledTest() override = default;
+
+ private:
+  base::test::ScopedFeatureList feature_list_;
+};
+
+TEST_F(SimpleIndexPrioritizedCachingDisabledTest,
+       EvictPrioritizationFeatureDisabled) {
   const auto caching_prioritization_period =
       net::features::kSimpleCachePrioritizedCachingPrioritizationPeriod.Get();
   auto now = base::Time::Now();