[base] Verify that process-wide FeatureList is not leaked by tests.

Bug: 875486
Change-Id: I902d0e8246d01239f31d7cefc88be069bdc69756
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1846043
Auto-Submit: Wez <wez@chromium.org>
Reviewed-by: Albert J. Wong <ajwong@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710875}

base/test/test_suite.cc

@@ -124,23 +124,31 @@ class CheckForLeakedGlobals : public testing::EmptyTestEventListener {
 
   // Check for leaks in individual tests.
   void OnTestStart(const testing::TestInfo& test) override {
+    feature_list_set_before_test_ = FeatureList::GetInstance();
     thread_pool_set_before_test_ = ThreadPoolInstance::Get();
   }
   void OnTestEnd(const testing::TestInfo& test) override {
+    DCHECK_EQ(feature_list_set_before_test_, FeatureList::GetInstance())
+        << " in test " << test.test_case_name() << "." << test.name();
     DCHECK_EQ(thread_pool_set_before_test_, ThreadPoolInstance::Get())
         << " in test " << test.test_case_name() << "." << test.name();
   }
 
   // Check for leaks in test cases (consisting of one or more tests).
   void OnTestCaseStart(const testing::TestCase& test_case) override {
+    feature_list_set_before_case_ = FeatureList::GetInstance();
     thread_pool_set_before_case_ = ThreadPoolInstance::Get();
   }
   void OnTestCaseEnd(const testing::TestCase& test_case) override {
+    DCHECK_EQ(feature_list_set_before_case_, FeatureList::GetInstance())
+        << " in case " << test_case.name();
     DCHECK_EQ(thread_pool_set_before_case_, ThreadPoolInstance::Get())
         << " in case " << test_case.name();
   }
 
  private:
+  FeatureList* feature_list_set_before_test_ = nullptr;
+  FeatureList* feature_list_set_before_case_ = nullptr;
   ThreadPoolInstance* thread_pool_set_before_test_ = nullptr;
   ThreadPoolInstance* thread_pool_set_before_case_ = nullptr;
 

chromecast/base/cast_features_unittest.cc

@@ -29,14 +29,23 @@ class CastFeaturesTest : public testing::Test {
   ~CastFeaturesTest() override {}
 
   // testing::Test implementation:
-  void SetUp() override { ResetCastFeaturesForTesting(); }
-  void TearDown() override { ResetCastFeaturesForTesting(); }
+  void SetUp() override {
+    original_feature_list_ = base::FeatureList::ClearInstanceForTesting();
+    ResetCastFeaturesForTesting();
+  }
+  void TearDown() override {
+    ResetCastFeaturesForTesting();
+    base::FeatureList::RestoreInstanceForTesting(
+        std::move(original_feature_list_));
+  }
 
  private:
   // A field trial list must be created before attempting to create FieldTrials.
   // In production, this instance lives in CastBrowserMainParts.
   base::FieldTrialList field_trial_list_;
 
+  std::unique_ptr<base::FeatureList> original_feature_list_;
+
   DISALLOW_COPY_AND_ASSIGN(CastFeaturesTest);
 };