Allow unit tests to force serial execution in the test launcher.

base/test/launcher/unit_test_launcher.cc

Index: base/test/launcher/unit_test_launcher.cc
diff --git a/base/test/launcher/unit_test_launcher.cc b/base/test/launcher/unit_test_launcher.cc
index 1b3a162c661ac25f419ed477764f5d935b467221..79831bbd0bc454d1d7e86c22d869be4ecb583f5c 100644
--- a/base/test/launcher/unit_test_launcher.cc
+++ b/base/test/launcher/unit_test_launcher.cc
@@ -557,9 +557,14 @@ size_t UnitTestLauncherDelegate::RunTests(
 
   int launch_flags = use_job_objects_ ? TestLauncher::USE_JOB_OBJECTS : 0;
 
+  std::vector<std::string> serialized;
   std::vector<std::string> batch;
-  for (size_t i = 0; i < test_names.size(); i++) {
-    batch.push_back(test_names[i]);
+  for (const auto& test_name : test_names) {
+    if (test_name.find(".SERIALIZE_") != std::string::npos) {
+      serialized.push_back(test_name);
+      continue;
+    }
+    batch.push_back(test_name);
 
     // Use 0 to indicate unlimited batch size.
     if (batch.size() >= batch_limit_ && batch_limit_ != 0) {
@@ -570,6 +575,9 @@ size_t UnitTestLauncherDelegate::RunTests(
 
   RunUnitTestsBatch(test_launcher, platform_delegate_, batch, launch_flags);
 
+  RunUnitTestsSerially(test_launcher, platform_delegate_, serialized,
+                       launch_flags);
+
   return test_names.size();
 }