Stack sampling profiler: handle unloaded and unloading modules

base/profiler/test_support_library.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Note: there is intentionally no header file associated with this library so
+// we don't risk implicitly demand loading it by accessing a symbol.
+
+#if defined(WIN32)
+#define BASE_PROFILER_TEST_SUPPORT_LIBRARY_EXPORT __declspec(dllexport)
+#else  // defined(WIN32)
+#define BASE_PROFILER_TEST_SUPPORT_LIBRARY_EXPORT __attribute__((visibility("default")))
+#endif
+
+namespace base {
+
+// Must be defined in an extern "C" block so we can look up the unmangled name.
+extern "C" {
+
+BASE_PROFILER_TEST_SUPPORT_LIBRARY_EXPORT void InvokeCallbackFunction(
+    void (*function)(void*),
+    void* arg) {
+  function(arg);
+  // Prevent tail call.
+  volatile int i = 0;
+  i = 1;
+}
+
+}  // extern "C"
+
+}  // namespace base