Add default options for ThreadSanitizer on Linux. Enable deadlock detection by default.

base/debug/sanitizer_options.cc

Index: base/debug/sanitizer_options.cc
diff --git a/base/debug/sanitizer_options.cc b/base/debug/sanitizer_options.cc
index 41f82b9840b59f118b575b82742e10cd446406ef..10024721574b5240ac7bef249c530d976a0fd902 100644
--- a/base/debug/sanitizer_options.cc
+++ b/base/debug/sanitizer_options.cc
@@ -70,3 +70,21 @@ const char *__asan_default_options() {
 }
 #endif  // OS_LINUX || OS_MACOSX
 #endif  // ADDRESS_SANITIZER
+
+#if defined(THREAD_SANITIZER) && defined(OS_LINUX)
+// Default options for ThreadSanitizer in various configurations:
+//   detect_deadlocks=1 - enable deadlock (lock inversion) detection.
+//   second_deadlock_stack=1 - more verbose deadlock reports.
+const char kTsanDefaultOptions[] = "detect_deadlocks=1 second_deadlock_stack=1";
+
+extern "C"
+__attribute__((no_sanitize_thread))
+__attribute__((visibility("default")))
+// The function isn't referenced from the executable itself. Make sure it isn't
+// stripped by the linker.
+__attribute__((used))
+const char *__tsan_default_options() {
+  return kTsanDefaultOptions;
+}
+
+#endif  // THREAD_SANITIZER && OS_LINUX