Use GetDefaultThreadStackSize() for mac sampling profiler

R=wittman@chromium.org

Change-Id: I171d11f25c2903894feb015adff53d6280a88be7
Reviewed-on: https://chromium-review.googlesource.com/c/1306496
Commit-Queue: ssid <ssid@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604722}

base/profiler/native_stack_sampler_mac.cc

@@ -518,17 +518,11 @@ std::unique_ptr<NativeStackSampler> NativeStackSampler::Create(
 
 // static
 size_t NativeStackSampler::GetStackBufferSize() {
-  // In platform_thread_mac's GetDefaultThreadStackSize(), RLIMIT_STACK is used
-  // for all stacks, not just the main thread's, so it is good for use here.
-  struct rlimit stack_rlimit;
-  if (getrlimit(RLIMIT_STACK, &stack_rlimit) == 0 &&
-      stack_rlimit.rlim_cur != RLIM_INFINITY) {
-    return stack_rlimit.rlim_cur;
-  }
+  size_t stack_size = PlatformThread::GetDefaultThreadStackSize();
 
   // If getrlimit somehow fails, return the default macOS main thread stack size
   // of 8 MB (DFLSSIZ in <i386/vmparam.h>) with extra wiggle room.
-  return 12 * 1024 * 1024;
+  return stack_size > 0 ? stack_size : 12 * 1024 * 1024;
 }
 
 }  // namespace base