Bump to WebRTC M120 release

Some API deprecation -- ExperimentalAgc and ExperimentalNs are gone.
We're continuing to carry iSAC even though it's gone upstream, but maybe
we'll want to drop that soon.

webrtc/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"
 
@@ -26,9 +30,15 @@ namespace field_trial {
 
 static const char* trials_init_string = NULL;
 
-#ifndef WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT
 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/"
@@ -68,9 +78,10 @@ bool FieldTrialsStringIsValidInternal(const absl::string_view trials) {
 
   return true;
 }
+
 }  // namespace
 
-bool FieldTrialsStringIsValid(const char* trials_string) {
+bool FieldTrialsStringIsValid(absl::string_view trials_string) {
   return FieldTrialsStringIsValidInternal(trials_string);
 }
 
@@ -78,18 +89,19 @@ void InsertOrReplaceFieldTrialStringsInMap(
     std::map<std::string, std::string>* fieldtrial_map,
     const absl::string_view trials_string) {
   if (FieldTrialsStringIsValidInternal(trials_string)) {
-    std::vector<std::string> tokens;
-    rtc::split(std::string(trials_string), '/', &tokens);
+    std::vector<absl::string_view> tokens = rtc::split(trials_string, '/');
     // Skip last token which is empty due to trailing '/'.
     for (size_t idx = 0; idx < tokens.size() - 1; idx += 2) {
-      (*fieldtrial_map)[tokens[idx]] = tokens[idx + 1];
+      (*fieldtrial_map)[std::string(tokens[idx])] =
+          std::string(tokens[idx + 1]);
     }
   } else {
-    RTC_DCHECK(false) << "Invalid field trials string:" << trials_string;
+    RTC_DCHECK_NOTREACHED() << "Invalid field trials string:" << trials_string;
   }
 }
 
-std::string MergeFieldTrialsStrings(const char* first, const char* second) {
+std::string MergeFieldTrialsStrings(absl::string_view first,
+                                    absl::string_view second) {
   std::map<std::string, std::string> fieldtrial_map;
   InsertOrReplaceFieldTrialStringsInMap(&fieldtrial_map, first);
   InsertOrReplaceFieldTrialStringsInMap(&fieldtrial_map, second);
@@ -102,11 +114,23 @@ std::string MergeFieldTrialsStrings(const char* first, const char* second) {
   return merged;
 }
 
-std::string FindFullName(const std::string& name) {
+#ifndef WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT
+std::string FindFullName(absl::string_view name) {
+#if WEBRTC_STRICT_FIELD_TRIALS == 1
+  RTC_DCHECK(absl::c_linear_search(kRegisteredFieldTrials, name) ||
+             TestKeys().contains(name))
+      << name << " is not registered, see g3doc/field-trials.md.";
+#elif WEBRTC_STRICT_FIELD_TRIALS == 2
+  RTC_LOG_IF(LS_WARNING,
+             !(absl::c_linear_search(kRegisteredFieldTrials, name) ||
+               TestKeys().contains(name)))
+      << name << " is not registered, see g3doc/field-trials.md.";
+#endif
+
   if (trials_init_string == NULL)
     return std::string();
 
-  std::string trials_string(trials_init_string);
+  absl::string_view trials_string(trials_init_string);
   if (trials_string.empty())
     return std::string();
 
@@ -122,14 +146,14 @@ std::string FindFullName(const std::string& name) {
     if (field_value_end == trials_string.npos ||
         field_value_end == field_name_end + 1)
       break;
-    std::string field_name(trials_string, next_item,
-                           field_name_end - next_item);
-    std::string field_value(trials_string, field_name_end + 1,
-                            field_value_end - field_name_end - 1);
+    absl::string_view field_name =
+        trials_string.substr(next_item, field_name_end - next_item);
+    absl::string_view field_value = trials_string.substr(
+        field_name_end + 1, field_value_end - field_name_end - 1);
     next_item = field_value_end + 1;
 
     if (name == field_name)
-      return field_value;
+      return std::string(field_value);
   }
   return std::string();
 }
@@ -138,12 +162,10 @@ std::string FindFullName(const std::string& name) {
 // Optionally initialize field trial from a string.
 void InitFieldTrialsFromString(const char* trials_string) {
   RTC_LOG(LS_INFO) << "Setting field trial string:" << trials_string;
-#ifndef WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT
   if (trials_string) {
     RTC_DCHECK(FieldTrialsStringIsValidInternal(trials_string))
         << "Invalid field trials string:" << trials_string;
   };
-#endif  // WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT
   trials_init_string = trials_string;
 }
 
@@ -151,5 +173,14 @@ const char* GetFieldTrialString() {
   return trials_init_string;
 }
 
+FieldTrialsAllowedInScopeForTesting::FieldTrialsAllowedInScopeForTesting(
+    flat_set<std::string> keys) {
+  TestKeys() = std::move(keys);
+}
+
+FieldTrialsAllowedInScopeForTesting::~FieldTrialsAllowedInScopeForTesting() {
+  TestKeys().clear();
+}
+
 }  // namespace field_trial
 }  // namespace webrtc