Use a less compiler-specific way for preventing inlining / tail-call optimization.

base/profiler/stack_sampling_profiler_unittest.cc

Index: base/profiler/stack_sampling_profiler_unittest.cc
diff --git a/base/profiler/stack_sampling_profiler_unittest.cc b/base/profiler/stack_sampling_profiler_unittest.cc
index dfccab4e1a893ae7da9c768f0e5c17aef4f9b692..ad9e92655719b6271fda394ba2fcb42711b32bbf 100644
--- a/base/profiler/stack_sampling_profiler_unittest.cc
+++ b/base/profiler/stack_sampling_profiler_unittest.cc
@@ -70,19 +70,16 @@ void TargetThread::SignalThreadToFinish() {
 }
 
 // static
-#if defined(_WIN64)
-// Disable optimizations for this function so that it gets its own stack frame.
-#pragma optimize("", off)
-#endif
-void TargetThread::SignalAndWaitUntilSignaled(
+// Disable inlining for this function so that it gets its own stack frame.
+NOINLINE void TargetThread::SignalAndWaitUntilSignaled(
     WaitableEvent* thread_started_event,
     WaitableEvent* finish_event) {
   thread_started_event->Signal();
+  volatile int x = 1;
   finish_event->Wait();
+  x = 0;  // Prevent tail call to WaitableEvent::Wait().
+  ALLOW_UNUSED_LOCAL(x);
 }
-#if defined(_WIN64)
-#pragma optimize("", on)
-#endif
 
 // Called on the profiler thread when complete. Collects profiles produced by
 // the profiler, and signals an event to allow the main thread to know that that