Update from https://crrev.com/306655

base/test/launcher/unit_test_launcher_ios.cc

Index: base/test/launcher/unit_test_launcher_ios.cc
diff --git a/base/test/launcher/unit_test_launcher_ios.cc b/base/test/launcher/unit_test_launcher_ios.cc
index ae08acd39a3373ca5e87afcf46ca33aa6ac9d85a..d4276c89bccf0e1e8c4de3898f9ffc73807d68fe 100644
--- a/base/test/launcher/unit_test_launcher_ios.cc
+++ b/base/test/launcher/unit_test_launcher_ios.cc
@@ -4,13 +4,31 @@
 
 #include "base/test/launcher/unit_test_launcher.h"
 
+#include "base/command_line.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/test/gtest_util.h"
+#include "base/test/test_switches.h"
+
 namespace base {
 
 int LaunchUnitTests(int argc,
                     char** argv,
                     const RunTestSuiteCallback& run_test_suite) {
-  // Stub implementation - iOS doesn't support features we need for
-  // the full test launcher (e.g. process_util).
+  CHECK(CommandLine::InitializedForCurrentProcess() ||
+        CommandLine::Init(argc, argv));
+  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kTestLauncherListTests)) {
+    FilePath list_path(command_line->GetSwitchValuePath(
+        switches::kTestLauncherListTests));
+    if (WriteCompiledInTestsToFile(list_path)) {
+      return 0;
+    } else {
+      LOG(ERROR) << "Failed to write list of tests.";
+      return 1;
+    }
+  }
+
   return run_test_suite.Run();
 }