diff --git a/api/BUILD.gn b/api/BUILD.gn
index f0bc7ba322..12511518f5 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -1362,6 +1362,25 @@ if (rtc_include_tests) {
   }
 }
 
+rtc_source_set("field_trials_registry") {
+  visibility = [ "*" ]
+  sources = [
+    "field_trials_registry.cc",
+    "field_trials_registry.h",
+  ]
+  deps = [
+    ":field_trials_view",
+    "../experiments:registered_field_trials",
+    "../rtc_base:checks",
+    "../rtc_base/containers:flat_set",
+    "../rtc_base/system:rtc_export",
+  ]
+  absl_deps = [
+    "//third_party/abseil-cpp/absl/algorithm:container",
+    "//third_party/abseil-cpp/absl/strings",
+  ]
+}
+
 rtc_source_set("field_trials_view") {
   visibility = [ "*" ]
   sources = [ "field_trials_view.h" ]
@@ -1382,7 +1401,7 @@ rtc_library("field_trials") {
     "field_trials.h",
   ]
   deps = [
-    ":field_trials_view",
+    ":field_trials_registry",
     "../rtc_base:checks",
     "../rtc_base/containers:flat_map",
     "../system_wrappers:field_trial",
diff --git a/api/DEPS b/api/DEPS
index c8c8ac0517..5f01204068 100644
--- a/api/DEPS
+++ b/api/DEPS
@@ -312,6 +312,10 @@ specific_include_rules = {
     "+rtc_base/thread.h",
   ],
 
+  "field_trials_registry\.h": [
+    "+rtc_base/containers/flat_set.h",
+  ],
+
   # .cc files in api/ should not be restricted in what they can #include,
   # so we re-add all the top-level directories here. (That's because .h
   # files leak their #includes to whoever's #including them, but .cc files
@@ -322,6 +326,7 @@ specific_include_rules = {
     "+common_audio",
     "+common_video",
     "+examples",
+    "+experiments",
     "+logging",
     "+media",
     "+modules",
diff --git a/api/field_trials.cc b/api/field_trials.cc
index d6b53acafb..4bd11271dc 100644
--- a/api/field_trials.cc
+++ b/api/field_trials.cc
@@ -90,7 +90,7 @@ FieldTrials::~FieldTrials() {
   }
 }
 
-std::string FieldTrials::Lookup(absl::string_view key) const {
+std::string FieldTrials::GetValue(absl::string_view key) const {
   auto it = key_value_map_.find(std::string(key));
   if (it != key_value_map_.end())
     return it->second;
diff --git a/api/field_trials.h b/api/field_trials.h
index 0bfa4b7871..bf7a7cc625 100644
--- a/api/field_trials.h
+++ b/api/field_trials.h
@@ -15,7 +15,7 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "api/field_trials_view.h"
+#include "api/field_trials_registry.h"
 #include "rtc_base/containers/flat_map.h"
 
 namespace webrtc {
@@ -34,7 +34,7 @@ namespace webrtc {
 // NOTE: Creating multiple FieldTrials-object is currently prohibited
 // until we remove the global string (TODO(bugs.webrtc.org/10335))
 // (unless using CreateNoGlobal):
-class FieldTrials : public FieldTrialsView {
+class FieldTrials : public FieldTrialsRegistry {
  public:
   explicit FieldTrials(const std::string& s);
   ~FieldTrials();
@@ -43,10 +43,11 @@ class FieldTrials : public FieldTrialsView {
   // global variable (i.e can not be used for all parts of webrtc).
   static std::unique_ptr<FieldTrials> CreateNoGlobal(const std::string& s);
 
-  std::string Lookup(absl::string_view key) const override;
-
  private:
   explicit FieldTrials(const std::string& s, bool);
+
+  std::string GetValue(absl::string_view key) const override;
+
   const bool uses_global_;
   const std::string field_trial_string_;
   const char* const previous_field_trial_string_;
diff --git a/api/field_trials_registry.cc b/api/field_trials_registry.cc
new file mode 100644
index 0000000000..f97e8a85a9
--- /dev/null
+++ b/api/field_trials_registry.cc
@@ -0,0 +1,31 @@
+/*
+ *  Copyright 2022 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "api/field_trials_registry.h"
+
+#include <string>
+
+#include "absl/algorithm/container.h"
+#include "absl/strings/string_view.h"
+#include "experiments/registered_field_trials.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/containers/flat_set.h"
+
+namespace webrtc {
+
+std::string FieldTrialsRegistry::Lookup(absl::string_view key) const {
+#if WEBRTC_STRICT_FIELD_TRIALS
+  RTC_DCHECK(absl::c_linear_search(kRegisteredFieldTrials, key) ||
+             test_keys_.contains(key))
+      << key << " is not registered.";
+#endif
+  return GetValue(key);
+}
+
+}  // namespace webrtc
diff --git a/api/field_trials_registry.h b/api/field_trials_registry.h
new file mode 100644
index 0000000000..dc7e8445b1
--- /dev/null
+++ b/api/field_trials_registry.h
@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2022 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef API_FIELD_TRIALS_REGISTRY_H_
+#define API_FIELD_TRIALS_REGISTRY_H_
+
+#include <string>
+#include <utility>
+
+#include "absl/strings/string_view.h"
+#include "api/field_trials_view.h"
+#include "rtc_base/containers/flat_set.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// Abstract base class for a field trial registry that verifies that any looked
+// up key has been pre-registered in accordance with `g3doc/field-trials.md`.
+class RTC_EXPORT FieldTrialsRegistry : public FieldTrialsView {
+ public:
+  FieldTrialsRegistry() = default;
+
+  FieldTrialsRegistry(const FieldTrialsRegistry&) = default;
+  FieldTrialsRegistry& operator=(const FieldTrialsRegistry&) = default;
+
+  ~FieldTrialsRegistry() override = default;
+
+  // Verifies that `key` is a registered field trial and then returns the
+  // configured value for `key` or an empty string if the field trial isn't
+  // configured.
+  std::string Lookup(absl::string_view key) const override;
+
+  // Register additional `keys` for testing. This should only be used for
+  // imaginary keys that are never used outside test code.
+  void RegisterKeysForTesting(flat_set<std::string> keys) {
+    test_keys_ = std::move(keys);
+  }
+
+ private:
+  virtual std::string GetValue(absl::string_view key) const = 0;
+
+  // Imaginary keys only used for testing.
+  flat_set<std::string> test_keys_;
+};
+
+}  // namespace webrtc
+
+#endif  // API_FIELD_TRIALS_REGISTRY_H_
diff --git a/api/field_trials_unittest.cc b/api/field_trials_unittest.cc
index 5f0188e557..2616a2e30c 100644
--- a/api/field_trials_unittest.cc
+++ b/api/field_trials_unittest.cc
@@ -34,6 +34,8 @@ using ::webrtc::field_trial::ScopedGlobalFieldTrialsForTesting;
 TEST(FieldTrialsTest, EmptyStringHasNoEffect) {
   ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial"});
   FieldTrials f("");
+  f.RegisterKeysForTesting({"MyCoolTrial"});
+
   EXPECT_FALSE(f.IsEnabled("MyCoolTrial"));
   EXPECT_FALSE(f.IsDisabled("MyCoolTrial"));
 }
@@ -43,6 +45,8 @@ TEST(FieldTrialsTest, EnabledDisabledMustBeFirstInValue) {
       "MyCoolTrial/EnabledFoo/"
       "MyUncoolTrial/DisabledBar/"
       "AnotherTrial/BazEnabled/");
+  f.RegisterKeysForTesting({"MyCoolTrial", "MyUncoolTrial", "AnotherTrial"});
+
   EXPECT_TRUE(f.IsEnabled("MyCoolTrial"));
   EXPECT_TRUE(f.IsDisabled("MyUncoolTrial"));
   EXPECT_FALSE(f.IsEnabled("AnotherTrial"));
@@ -53,6 +57,8 @@ TEST(FieldTrialsTest, FieldTrialsDoesNotReadGlobalString) {
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrials f("");
+  f.RegisterKeysForTesting({"MyCoolTrial", "MyUncoolTrial"});
+
   EXPECT_FALSE(f.IsEnabled("MyCoolTrial"));
   EXPECT_FALSE(f.IsDisabled("MyUncoolTrial"));
 }
@@ -93,6 +99,8 @@ TEST(FieldTrialsTest, NonGlobalFieldTrialsInstanceDoesNotModifyGlobalString) {
   std::unique_ptr<FieldTrials> f =
       FieldTrials::CreateNoGlobal("SomeString/Enabled/");
   ASSERT_THAT(f, NotNull());
+  f->RegisterKeysForTesting({"SomeString"});
+
   EXPECT_TRUE(f->IsEnabled("SomeString"));
   EXPECT_FALSE(webrtc::field_trial::IsEnabled("SomeString"));
 }
@@ -104,6 +112,8 @@ TEST(FieldTrialsTest, NonGlobalFieldTrialsSupportSimultaneousInstances) {
       FieldTrials::CreateNoGlobal("SomeOtherString/Enabled/");
   ASSERT_THAT(f1, NotNull());
   ASSERT_THAT(f2, NotNull());
+  f1->RegisterKeysForTesting({"SomeString", "SomeOtherString"});
+  f2->RegisterKeysForTesting({"SomeString", "SomeOtherString"});
 
   EXPECT_TRUE(f1->IsEnabled("SomeString"));
   EXPECT_FALSE(f1->IsEnabled("SomeOtherString"));
@@ -118,6 +128,8 @@ TEST(FieldTrialsTest, GlobalAndNonGlobalFieldTrialsAreDisjoint) {
   std::unique_ptr<FieldTrials> f2 =
       FieldTrials::CreateNoGlobal("SomeOtherString/Enabled/");
   ASSERT_THAT(f2, NotNull());
+  f1.RegisterKeysForTesting({"SomeString", "SomeOtherString"});
+  f2->RegisterKeysForTesting({"SomeString", "SomeOtherString"});
 
   EXPECT_TRUE(f1.IsEnabled("SomeString"));
   EXPECT_FALSE(f1.IsEnabled("SomeOtherString"));
@@ -131,6 +143,8 @@ TEST(FieldTrialsTest, FieldTrialBasedConfigReadsGlobalString) {
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrialBasedConfig f;
+  f.RegisterKeysForTesting({"MyCoolTrial", "MyUncoolTrial"});
+
   EXPECT_TRUE(f.IsEnabled("MyCoolTrial"));
   EXPECT_TRUE(f.IsDisabled("MyUncoolTrial"));
 }
diff --git a/api/field_trials_view.h b/api/field_trials_view.h
index 299205d1d3..45e6f7899b 100644
--- a/api/field_trials_view.h
+++ b/api/field_trials_view.h
@@ -17,15 +17,18 @@
 
 namespace webrtc {
 
-// An interface that provides a key-value mapping for configuring internal
-// details of WebRTC. Note that there's no guarantess that the meaning of a
-// particular key value mapping will be preserved over time and no announcements
-// will be made if they are changed. It's up to the library user to ensure that
-// the behavior does not break.
+// An interface that provides the means to access field trials.
+//
+// Note that there are no guarantess that the meaning of a particular key-value
+// mapping will be preserved over time and no announcements will be made if they
+// are changed. It's up to the library user to ensure that the behavior does not
+// break.
 class RTC_EXPORT FieldTrialsView {
  public:
   virtual ~FieldTrialsView() = default;
-  // The configured value for the given key. Defaults to an empty string.
+
+  // Returns the configured value for `key` or an empty string if the field
+  // trial isn't configured.
   virtual std::string Lookup(absl::string_view key) const = 0;
 
   bool IsEnabled(absl::string_view key) const {
diff --git a/api/transport/BUILD.gn b/api/transport/BUILD.gn
index 3cc3559f30..86a7c8acf8 100644
--- a/api/transport/BUILD.gn
+++ b/api/transport/BUILD.gn
@@ -52,7 +52,7 @@ rtc_library("field_trial_based_config") {
     "field_trial_based_config.h",
   ]
   deps = [
-    "../../api:field_trials_view",
+    "../../api:field_trials_registry",
     "../../system_wrappers:field_trial",
   ]
   absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
diff --git a/api/transport/field_trial_based_config.cc b/api/transport/field_trial_based_config.cc
index 4a3a179240..0cef30f054 100644
--- a/api/transport/field_trial_based_config.cc
+++ b/api/transport/field_trial_based_config.cc
@@ -12,7 +12,7 @@
 #include "system_wrappers/include/field_trial.h"
 
 namespace webrtc {
-std::string FieldTrialBasedConfig::Lookup(absl::string_view key) const {
+std::string FieldTrialBasedConfig::GetValue(absl::string_view key) const {
   return webrtc::field_trial::FindFullName(std::string(key));
 }
 }  // namespace webrtc
diff --git a/api/transport/field_trial_based_config.h b/api/transport/field_trial_based_config.h
index f0063ff95e..d47140e579 100644
--- a/api/transport/field_trial_based_config.h
+++ b/api/transport/field_trial_based_config.h
@@ -13,13 +13,13 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "api/field_trials_view.h"
+#include "api/field_trials_registry.h"
 
 namespace webrtc {
 // Implementation using the field trial API fo the key value lookup.
-class FieldTrialBasedConfig : public FieldTrialsView {
- public:
-  std::string Lookup(absl::string_view key) const override;
+class FieldTrialBasedConfig : public FieldTrialsRegistry {
+ private:
+  std::string GetValue(absl::string_view key) const override;
 };
 }  // namespace webrtc
 
diff --git a/modules/rtp_rtcp/BUILD.gn b/modules/rtp_rtcp/BUILD.gn
index 736ca58fd1..ead114bc91 100644
--- a/modules/rtp_rtcp/BUILD.gn
+++ b/modules/rtp_rtcp/BUILD.gn
@@ -604,6 +604,7 @@ if (rtc_include_tests) {
       ":rtp_rtcp_legacy",
       "../../api:array_view",
       "../../api:create_time_controller",
+      "../../api:field_trials_registry",
       "../../api:libjingle_peerconnection_api",
       "../../api:mock_frame_encryptor",
       "../../api:rtp_headers",
diff --git a/modules/rtp_rtcp/source/rtp_rtcp_impl2_unittest.cc b/modules/rtp_rtcp/source/rtp_rtcp_impl2_unittest.cc
index 4c08ce5c13..4dece662ec 100644
--- a/modules/rtp_rtcp/source/rtp_rtcp_impl2_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_rtcp_impl2_unittest.cc
@@ -17,7 +17,7 @@
 #include <utility>
 
 #include "absl/types/optional.h"
-#include "api/transport/field_trial_based_config.h"
+#include "api/field_trials_registry.h"
 #include "api/units/time_delta.h"
 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "modules/rtp_rtcp/source/rtcp_packet.h"
@@ -157,7 +157,7 @@ struct TestConfig {
   bool with_overhead = false;
 };
 
-class FieldTrialConfig : public FieldTrialsView {
+class FieldTrialConfig : public FieldTrialsRegistry {
  public:
   static FieldTrialConfig GetFromTestConfig(const TestConfig& config) {
     FieldTrialConfig trials;
@@ -170,14 +170,14 @@ class FieldTrialConfig : public FieldTrialsView {
 
   void SetOverHeadEnabled(bool enabled) { overhead_enabled_ = enabled; }
 
-  std::string Lookup(absl::string_view key) const override {
+ private:
+  std::string GetValue(absl::string_view key) const override {
     if (key == "WebRTC-SendSideBwe-WithOverhead") {
       return overhead_enabled_ ? "Enabled" : "Disabled";
     }
     return "";
   }
 
- private:
   bool overhead_enabled_;
 };
 
diff --git a/modules/rtp_rtcp/source/rtp_sender_egress_unittest.cc b/modules/rtp_rtcp/source/rtp_sender_egress_unittest.cc
index 982f3fed9d..19e122f8e2 100644
--- a/modules/rtp_rtcp/source/rtp_sender_egress_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_egress_unittest.cc
@@ -15,6 +15,7 @@
 #include "absl/types/optional.h"
 #include "api/array_view.h"
 #include "api/call/transport.h"
+#include "api/field_trials_registry.h"
 #include "api/units/data_size.h"
 #include "api/units/timestamp.h"
 #include "logging/rtc_event_log/mock/mock_rtc_event_log.h"
@@ -87,21 +88,21 @@ class MockSendSideDelayObserver : public SendSideDelayObserver {
               (override));
 };
 
-class FieldTrialConfig : public FieldTrialsView {
+class FieldTrialConfig : public FieldTrialsRegistry {
  public:
   FieldTrialConfig() : overhead_enabled_(false) {}
   ~FieldTrialConfig() override {}
 
   void SetOverHeadEnabled(bool enabled) { overhead_enabled_ = enabled; }
 
-  std::string Lookup(absl::string_view key) const override {
+ private:
+  std::string GetValue(absl::string_view key) const override {
     if (key == "WebRTC-SendSideBwe-WithOverhead") {
       return overhead_enabled_ ? "Enabled" : "Disabled";
     }
     return "";
   }
 
- private:
   bool overhead_enabled_;
 };
 
diff --git a/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc b/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
index a4d669edc5..13527128c9 100644
--- a/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
@@ -16,6 +16,7 @@
 #include <vector>
 
 #include "absl/memory/memory.h"
+#include "api/field_trials_registry.h"
 #include "api/rtp_headers.h"
 #include "api/task_queue/task_queue_base.h"
 #include "api/task_queue/task_queue_factory.h"
@@ -148,7 +149,7 @@ class TestRtpSenderVideo : public RTPSenderVideo {
   }
 };
 
-class FieldTrials : public FieldTrialsView {
+class FieldTrials : public FieldTrialsRegistry {
  public:
   explicit FieldTrials(bool use_send_side_bwe_with_overhead)
       : use_send_side_bwe_with_overhead_(use_send_side_bwe_with_overhead),
@@ -158,7 +159,8 @@ class FieldTrials : public FieldTrialsView {
     include_capture_clock_offset_ = include_capture_clock_offset;
   }
 
-  std::string Lookup(absl::string_view key) const override {
+ private:
+  std::string GetValue(absl::string_view key) const override {
     if (key == "WebRTC-SendSideBwe-WithOverhead") {
       return use_send_side_bwe_with_overhead_ ? "Enabled" : "";
     } else if (key == "WebRTC-IncludeCaptureClockOffset") {
@@ -167,7 +169,6 @@ class FieldTrials : public FieldTrialsView {
     return "";
   }
 
- private:
   bool use_send_side_bwe_with_overhead_;
   bool include_capture_clock_offset_;
 };
diff --git a/test/BUILD.gn b/test/BUILD.gn
index 8d226d9c72..f2e574a7c7 100644
--- a/test/BUILD.gn
+++ b/test/BUILD.gn
@@ -255,7 +255,7 @@ rtc_library("explicit_key_value_config") {
   ]
 
   deps = [
-    "../api:field_trials_view",
+    "../api:field_trials_registry",
     "../rtc_base:checks",
   ]
   absl_deps = [ "//third_party/abseil-cpp/absl/strings:strings" ]
@@ -271,7 +271,7 @@ rtc_library("scoped_key_value_config") {
 
   deps = [
     ":field_trial",
-    "../api:field_trials_view",
+    "../api:field_trials_registry",
     "../rtc_base:checks",
     "../system_wrappers:field_trial",
   ]
diff --git a/test/explicit_key_value_config.cc b/test/explicit_key_value_config.cc
index c9e5ac1c28..90690c0514 100644
--- a/test/explicit_key_value_config.cc
+++ b/test/explicit_key_value_config.cc
@@ -11,7 +11,6 @@
 #include "test/explicit_key_value_config.h"
 
 #include "absl/strings/string_view.h"
-#include "api/field_trials_view.h"
 #include "rtc_base/checks.h"
 
 namespace webrtc {
@@ -46,7 +45,7 @@ ExplicitKeyValueConfig::ExplicitKeyValueConfig(absl::string_view s) {
   RTC_CHECK_EQ(field_start, s.size());
 }
 
-std::string ExplicitKeyValueConfig::Lookup(absl::string_view key) const {
+std::string ExplicitKeyValueConfig::GetValue(absl::string_view key) const {
   auto it = key_value_map_.find(key);
   if (it != key_value_map_.end())
     return it->second;
diff --git a/test/explicit_key_value_config.h b/test/explicit_key_value_config.h
index 5685c13604..f14a10432c 100644
--- a/test/explicit_key_value_config.h
+++ b/test/explicit_key_value_config.h
@@ -16,17 +16,18 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "api/field_trials_view.h"
+#include "api/field_trials_registry.h"
 
 namespace webrtc {
 namespace test {
 
-class ExplicitKeyValueConfig : public FieldTrialsView {
+class ExplicitKeyValueConfig : public FieldTrialsRegistry {
  public:
   explicit ExplicitKeyValueConfig(absl::string_view s);
-  std::string Lookup(absl::string_view key) const override;
 
  private:
+  std::string GetValue(absl::string_view key) const override;
+
   // Unlike std::less<std::string>, std::less<> is transparent and allows
   // heterogeneous lookup directly with absl::string_view.
   std::map<std::string, std::string, std::less<>> key_value_map_;
diff --git a/test/scoped_key_value_config.cc b/test/scoped_key_value_config.cc
index 449d5f0722..df84462637 100644
--- a/test/scoped_key_value_config.cc
+++ b/test/scoped_key_value_config.cc
@@ -10,7 +10,6 @@
 
 #include "test/scoped_key_value_config.h"
 
-#include "api/field_trials_view.h"
 #include "rtc_base/checks.h"
 #include "system_wrappers/include/field_trial.h"
 #include "test/field_trial.h"
@@ -97,7 +96,7 @@ ScopedKeyValueConfig* ScopedKeyValueConfig::GetRoot(ScopedKeyValueConfig* n) {
   return n;
 }
 
-std::string ScopedKeyValueConfig::Lookup(absl::string_view key) const {
+std::string ScopedKeyValueConfig::GetValue(absl::string_view key) const {
   if (parent_ == nullptr) {
     return leaf_->LookupRecurse(key);
   } else {
diff --git a/test/scoped_key_value_config.h b/test/scoped_key_value_config.h
index db90ca3533..c0023f8228 100644
--- a/test/scoped_key_value_config.h
+++ b/test/scoped_key_value_config.h
@@ -17,24 +17,23 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "api/field_trials_view.h"
+#include "api/field_trials_registry.h"
 #include "test/field_trial.h"
 
 namespace webrtc {
 namespace test {
 
-class ScopedKeyValueConfig : public FieldTrialsView {
+class ScopedKeyValueConfig : public FieldTrialsRegistry {
  public:
   virtual ~ScopedKeyValueConfig();
   ScopedKeyValueConfig();
   explicit ScopedKeyValueConfig(absl::string_view s);
   ScopedKeyValueConfig(ScopedKeyValueConfig& parent, absl::string_view s);
 
-  std::string Lookup(absl::string_view key) const override;
-
  private:
   ScopedKeyValueConfig(ScopedKeyValueConfig* parent, absl::string_view s);
   ScopedKeyValueConfig* GetRoot(ScopedKeyValueConfig* n);
+  std::string GetValue(absl::string_view key) const override;
   std::string LookupRecurse(absl::string_view key) const;
 
   ScopedKeyValueConfig* const parent_;