diff --git a/BUILD.gn b/BUILD.gn
index f962484..ca60bdc 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -273,6 +273,12 @@
     defines += [ "WEBRTC_ENABLE_PROTOBUF=0" ]
   }
 
+  if (rtc_strict_field_trials) {
+    defines += [ "WEBRTC_STRICT_FIELD_TRIALS=1" ]
+  } else {
+    defines += [ "WEBRTC_STRICT_FIELD_TRIALS=0" ]
+  }
+
   if (rtc_include_internal_audio_device) {
     defines += [ "WEBRTC_INCLUDE_INTERNAL_AUDIO_DEVICE" ]
   }
diff --git a/api/BUILD.gn b/api/BUILD.gn
index 147a8c1..f0bc7ba 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -1308,6 +1308,7 @@
       "../rtc_base:rtc_event",
       "../rtc_base:rtc_task_queue",
       "../rtc_base:task_queue_for_test",
+      "../rtc_base/containers:flat_set",
       "../rtc_base/task_utils:repeating_task",
       "../system_wrappers:field_trial",
       "../test:fileutils",
@@ -1322,7 +1323,10 @@
       "video:rtp_video_frame_assembler_unittests",
       "video:video_unittests",
     ]
-    absl_deps = [ "//third_party/abseil-cpp/absl/types:optional" ]
+    absl_deps = [
+      "//third_party/abseil-cpp/absl/strings",
+      "//third_party/abseil-cpp/absl/types:optional",
+    ]
   }
 
   rtc_library("compile_all_headers") {
diff --git a/api/field_trials_unittest.cc b/api/field_trials_unittest.cc
index dc82898..5f0188e 100644
--- a/api/field_trials_unittest.cc
+++ b/api/field_trials_unittest.cc
@@ -11,8 +11,11 @@
 #include "api/field_trials.h"
 
 #include <memory>
+#include <utility>
 
+#include "absl/strings/string_view.h"
 #include "api/transport/field_trial_based_config.h"
+#include "rtc_base/containers/flat_set.h"
 #include "system_wrappers/include/field_trial.h"
 #include "test/gmock.h"
 #include "test/gtest.h"
@@ -26,22 +29,16 @@
 
 using ::testing::NotNull;
 using ::webrtc::field_trial::InitFieldTrialsFromString;
+using ::webrtc::field_trial::ScopedGlobalFieldTrialsForTesting;
 
-class FieldTrialsTest : public testing::Test {
- protected:
-  FieldTrialsTest() {
-    // Make sure global state is consistent between test runs.
-    InitFieldTrialsFromString(nullptr);
-  }
-};
-
-TEST_F(FieldTrialsTest, EmptyStringHasNoEffect) {
+TEST(FieldTrialsTest, EmptyStringHasNoEffect) {
+  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial"});
   FieldTrials f("");
   EXPECT_FALSE(f.IsEnabled("MyCoolTrial"));
   EXPECT_FALSE(f.IsDisabled("MyCoolTrial"));
 }
 
-TEST_F(FieldTrialsTest, EnabledDisabledMustBeFirstInValue) {
+TEST(FieldTrialsTest, EnabledDisabledMustBeFirstInValue) {
   FieldTrials f(
       "MyCoolTrial/EnabledFoo/"
       "MyUncoolTrial/DisabledBar/"
@@ -51,7 +48,8 @@
   EXPECT_FALSE(f.IsEnabled("AnotherTrial"));
 }
 
-TEST_F(FieldTrialsTest, FieldTrialsDoesNotReadGlobalString) {
+TEST(FieldTrialsTest, FieldTrialsDoesNotReadGlobalString) {
+  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrials f("");
@@ -59,13 +57,14 @@
   EXPECT_FALSE(f.IsDisabled("MyUncoolTrial"));
 }
 
-TEST_F(FieldTrialsTest, FieldTrialsWritesGlobalString) {
+TEST(FieldTrialsTest, FieldTrialsWritesGlobalString) {
+  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
   FieldTrials f("MyCoolTrial/Enabled/MyUncoolTrial/Disabled/");
   EXPECT_TRUE(webrtc::field_trial::IsEnabled("MyCoolTrial"));
   EXPECT_TRUE(webrtc::field_trial::IsDisabled("MyUncoolTrial"));
 }
 
-TEST_F(FieldTrialsTest, FieldTrialsRestoresGlobalStringAfterDestruction) {
+TEST(FieldTrialsTest, FieldTrialsRestoresGlobalStringAfterDestruction) {
   static constexpr char s[] = "SomeString/Enabled/";
   InitFieldTrialsFromString(s);
   {
@@ -77,19 +76,20 @@
 }
 
 #if GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
-TEST_F(FieldTrialsTest, FieldTrialsDoesNotSupportSimultaneousInstances) {
+TEST(FieldTrialsTest, FieldTrialsDoesNotSupportSimultaneousInstances) {
   FieldTrials f("SomeString/Enabled/");
   RTC_EXPECT_DEATH(FieldTrials("SomeOtherString/Enabled/").Lookup("Whatever"),
                    "Only one instance");
 }
 #endif  // GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
 
-TEST_F(FieldTrialsTest, FieldTrialsSupportsSeparateInstances) {
+TEST(FieldTrialsTest, FieldTrialsSupportsSeparateInstances) {
   { FieldTrials f("SomeString/Enabled/"); }
   { FieldTrials f("SomeOtherString/Enabled/"); }
 }
 
-TEST_F(FieldTrialsTest, NonGlobalFieldTrialsInstanceDoesNotModifyGlobalString) {
+TEST(FieldTrialsTest, NonGlobalFieldTrialsInstanceDoesNotModifyGlobalString) {
+  ScopedGlobalFieldTrialsForTesting g({"SomeString"});
   std::unique_ptr<FieldTrials> f =
       FieldTrials::CreateNoGlobal("SomeString/Enabled/");
   ASSERT_THAT(f, NotNull());
@@ -97,7 +97,7 @@
   EXPECT_FALSE(webrtc::field_trial::IsEnabled("SomeString"));
 }
 
-TEST_F(FieldTrialsTest, NonGlobalFieldTrialsSupportSimultaneousInstances) {
+TEST(FieldTrialsTest, NonGlobalFieldTrialsSupportSimultaneousInstances) {
   std::unique_ptr<FieldTrials> f1 =
       FieldTrials::CreateNoGlobal("SomeString/Enabled/");
   std::unique_ptr<FieldTrials> f2 =
@@ -112,7 +112,8 @@
   EXPECT_TRUE(f2->IsEnabled("SomeOtherString"));
 }
 
-TEST_F(FieldTrialsTest, GlobalAndNonGlobalFieldTrialsAreDisjoint) {
+TEST(FieldTrialsTest, GlobalAndNonGlobalFieldTrialsAreDisjoint) {
+  ScopedGlobalFieldTrialsForTesting g({"SomeString", "SomeOtherString"});
   FieldTrials f1("SomeString/Enabled/");
   std::unique_ptr<FieldTrials> f2 =
       FieldTrials::CreateNoGlobal("SomeOtherString/Enabled/");
@@ -125,7 +126,8 @@
   EXPECT_TRUE(f2->IsEnabled("SomeOtherString"));
 }
 
-TEST_F(FieldTrialsTest, FieldTrialBasedConfigReadsGlobalString) {
+TEST(FieldTrialsTest, FieldTrialBasedConfigReadsGlobalString) {
+  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrialBasedConfig f;
diff --git a/rtc_base/experiments/field_trial_parser_unittest.cc b/rtc_base/experiments/field_trial_parser_unittest.cc
index 9916ede..ea42352 100644
--- a/rtc_base/experiments/field_trial_parser_unittest.cc
+++ b/rtc_base/experiments/field_trial_parser_unittest.cc
@@ -18,7 +18,8 @@
 
 namespace webrtc {
 namespace {
-const char kDummyExperiment[] = "WebRTC-DummyExperiment";
+
+constexpr char kDummyExperiment[] = "WebRTC-DummyExperiment";
 
 struct DummyExperiment {
   FieldTrialFlag enabled = FieldTrialFlag("Enabled");
@@ -29,6 +30,8 @@
   FieldTrialParameter<std::string> hash =
       FieldTrialParameter<std::string>("h", "a80");
 
+  field_trial::ScopedGlobalFieldTrialsForTesting g{{kDummyExperiment}};
+
   explicit DummyExperiment(absl::string_view field_trial) {
     ParseFieldTrial({&enabled, &factor, &retries, &size, &ping, &hash},
                     field_trial);
diff --git a/system_wrappers/BUILD.gn b/system_wrappers/BUILD.gn
index c979a6a..a6bcc9c 100644
--- a/system_wrappers/BUILD.gn
+++ b/system_wrappers/BUILD.gn
@@ -87,11 +87,16 @@
     defines = [ "WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT" ]
   }
   deps = [
+    "../experiments:registered_field_trials",
     "../rtc_base:checks",
     "../rtc_base:logging",
     "../rtc_base:stringutils",
+    "../rtc_base/containers:flat_set",
   ]
-  absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
+  absl_deps = [
+    "//third_party/abseil-cpp/absl/algorithm:container",
+    "//third_party/abseil-cpp/absl/strings",
+  ]
 }
 
 rtc_library("metrics") {
diff --git a/system_wrappers/include/field_trial.h b/system_wrappers/include/field_trial.h
index eb57f29..ffbd864 100644
--- a/system_wrappers/include/field_trial.h
+++ b/system_wrappers/include/field_trial.h
@@ -14,6 +14,7 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
+#include "rtc_base/containers/flat_set.h"
 
 // Field trials allow webrtc clients (such as Chrome) to turn on feature code
 // in binaries out in the field and gather information with that.
@@ -97,6 +98,13 @@
 std::string MergeFieldTrialsStrings(absl::string_view first,
                                     absl::string_view second);
 
+// RAII type that ensures global state is consistent between tests.
+class ScopedGlobalFieldTrialsForTesting {
+ public:
+  explicit ScopedGlobalFieldTrialsForTesting(flat_set<std::string> keys);
+  ~ScopedGlobalFieldTrialsForTesting();
+};
+
 }  // namespace field_trial
 }  // namespace webrtc
 
diff --git a/system_wrappers/source/DEPS b/system_wrappers/source/DEPS
new file mode 100644
index 0000000..ac7f5a2
--- /dev/null
+++ b/system_wrappers/source/DEPS
@@ -0,0 +1,6 @@
+specific_include_rules = {
+  # TODO(bugs.webrtc.org/10335): Remove rule when global string is removed.
+  "field_trial\.cc": [
+    "+experiments/registered_field_trials.h",
+  ],
+}
diff --git a/system_wrappers/source/field_trial.cc b/system_wrappers/source/field_trial.cc
index f83876b..bdf84bd 100644
--- a/system_wrappers/source/field_trial.cc
+++ b/system_wrappers/source/field_trial.cc
@@ -13,9 +13,13 @@
 
 #include <map>
 #include <string>
+#include <utility>
 
+#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"
 #include "rtc_base/logging.h"
 #include "rtc_base/string_encode.h"
 
@@ -27,7 +31,14 @@
 static const char* trials_init_string = NULL;
 
 namespace {
+
 constexpr char kPersistentStringSeparator = '/';
+
+flat_set<std::string>& TestKeys() {
+  static auto* test_keys = new flat_set<std::string>();
+  return *test_keys;
+}
+
 // Validates the given field trial string.
 //  E.g.:
 //    "WebRTC-experimentFoo/Enabled/WebRTC-experimentBar/Enabled100kbps/"
@@ -67,6 +78,7 @@
 
   return true;
 }
+
 }  // namespace
 
 bool FieldTrialsStringIsValid(absl::string_view trials_string) {
@@ -104,6 +116,12 @@
 
 #ifndef WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT
 std::string FindFullName(absl::string_view name) {
+#if WEBRTC_STRICT_FIELD_TRIALS
+  RTC_DCHECK(absl::c_linear_search(kRegisteredFieldTrials, name) ||
+             TestKeys().contains(name))
+      << name << " is not registered.";
+#endif
+
   if (trials_init_string == NULL)
     return std::string();
 
@@ -150,5 +168,14 @@
   return trials_init_string;
 }
 
+ScopedGlobalFieldTrialsForTesting::ScopedGlobalFieldTrialsForTesting(
+    flat_set<std::string> keys) {
+  TestKeys() = std::move(keys);
+}
+
+ScopedGlobalFieldTrialsForTesting::~ScopedGlobalFieldTrialsForTesting() {
+  TestKeys().clear();
+}
+
 }  // namespace field_trial
 }  // namespace webrtc
diff --git a/webrtc.gni b/webrtc.gni
index 8ab7b27..8dfcc9d 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -231,6 +231,11 @@
 
   # Includes the dav1d decoder in the internal decoder factory when set to true.
   rtc_include_dav1d_in_internal_decoder_factory = true
+
+  # When set to true, a run-time check will make sure that all field trial keys
+  # have been registered in accordance with the field trial policy. The check
+  # will only run with builds that have RTC_DCHECKs enabled.
+  rtc_strict_field_trials = false
 }
 
 if (!build_with_mozilla) {