From d69998aa5c4f781aa08efed3bafe0a4e25f38338 Mon Sep 17 00:00:00 2001
From: Sebastian Jansson <srte@webrtc.org>
Date: Thu, 20 Dec 2018 12:25:19 +0100
Subject: [PATCH] Adds support for empty key fields in field trial parser.

Bug: webrtc:9346
Change-Id: I16e068340d3d48b983270af0c481ed538632e148
Reviewed-on: https://webrtc-review.googlesource.com/c/115241
Reviewed-by: Christoffer Rodbro <crodbro@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26070}
---
 rtc_base/experiments/field_trial_parser.cc          | 13 ++++++++++++-
 rtc_base/experiments/field_trial_parser.h           |  2 +-
 rtc_base/experiments/field_trial_parser_unittest.cc |  8 ++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/rtc_base/experiments/field_trial_parser.cc b/rtc_base/experiments/field_trial_parser.cc
index 936487cb01..f823b48e53 100644
--- a/rtc_base/experiments/field_trial_parser.cc
+++ b/rtc_base/experiments/field_trial_parser.cc
@@ -41,9 +41,15 @@ void ParseFieldTrial(
     std::initializer_list<FieldTrialParameterInterface*> fields,
     std::string trial_string) {
   std::map<std::string, FieldTrialParameterInterface*> field_map;
+  FieldTrialParameterInterface* keyless_field = nullptr;
   for (FieldTrialParameterInterface* field : fields) {
     field->MarkAsUsed();
-    field_map[field->Key()] = field;
+    if (field->Key().empty()) {
+      RTC_DCHECK(!keyless_field);
+      keyless_field = field;
+    } else {
+      field_map[field->Key()] = field;
+    }
   }
   size_t i = 0;
   while (i < trial_string.length()) {
@@ -62,6 +68,11 @@ void ParseFieldTrial(
         RTC_LOG(LS_WARNING) << "Failed to read field with key: '" << key
                             << "' in trial: \"" << trial_string << "\"";
       }
+    } else if (!opt_value && keyless_field && !key.empty()) {
+      if (!keyless_field->Parse(key)) {
+        RTC_LOG(LS_WARNING) << "Failed to read empty key field with value '"
+                            << key << "' in trial: \"" << trial_string << "\"";
+      }
     } else {
       RTC_LOG(LS_INFO) << "No field with key: '" << key
                        << "' (found in trial: \"" << trial_string << "\")";
diff --git a/rtc_base/experiments/field_trial_parser.h b/rtc_base/experiments/field_trial_parser.h
index 8bdd9b5d8e..0330f1970a 100644
--- a/rtc_base/experiments/field_trial_parser.h
+++ b/rtc_base/experiments/field_trial_parser.h
@@ -55,7 +55,7 @@ class FieldTrialParameterInterface {
 };
 
 // ParseFieldTrial function parses the given string and fills the given fields
-// with extrated values if available.
+// with extracted values if available.
 void ParseFieldTrial(
     std::initializer_list<FieldTrialParameterInterface*> fields,
     std::string raw_string);
diff --git a/rtc_base/experiments/field_trial_parser_unittest.cc b/rtc_base/experiments/field_trial_parser_unittest.cc
index 0d067f5a49..806b895e5f 100644
--- a/rtc_base/experiments/field_trial_parser_unittest.cc
+++ b/rtc_base/experiments/field_trial_parser_unittest.cc
@@ -112,6 +112,14 @@ TEST(FieldTrialParserTest, IgnoresOutOfRange) {
   EXPECT_EQ(low.Get(), 20);
   EXPECT_EQ(high.Get(), 20);
 }
+TEST(FieldTrialParserTest, ReadsValuesFromFieldWithoutKey) {
+  FieldTrialFlag enabled("Enabled");
+  FieldTrialParameter<int> req("", 10);
+  ParseFieldTrial({&enabled, &req}, "Enabled,20");
+  EXPECT_EQ(req.Get(), 20);
+  ParseFieldTrial({&req}, "30");
+  EXPECT_EQ(req.Get(), 30);
+}
 TEST(FieldTrialParserTest, ParsesOptionalParameters) {
   FieldTrialOptional<int> max_count("c", absl::nullopt);
   ParseFieldTrial({&max_count}, "");