Fix data race with synthetic delay initialization

base/debug/trace_event_synthetic_delay_unittest.cc

Index: base/debug/trace_event_synthetic_delay_unittest.cc
diff --git a/base/debug/trace_event_synthetic_delay_unittest.cc b/base/debug/trace_event_synthetic_delay_unittest.cc
index 7833e7bbcdeb89d47bc2bb404e280cf962f48260..5b9c20d2fa428f07e0d3c432a2f8f87976558981 100644
--- a/base/debug/trace_event_synthetic_delay_unittest.cc
+++ b/base/debug/trace_event_synthetic_delay_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "base/debug/trace_event_synthetic_delay.h"
 
+#include "base/threading/simple_thread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ -14,6 +15,7 @@ const int kTargetDurationMs = 100;
 // Allow some leeway in timings to make it possible to run these tests with a
 // wall clock time source too.
 const int kShortDurationMs = 10;
+const char kThreadedDelayName[] = "test.ThreadedDelay";
 
 }  // namespace
 
@@ -152,5 +154,34 @@ TEST_F(TraceEventSyntheticDelayTest, BeginParallel) {
   EXPECT_LT((Now() - start_time).InMilliseconds(), kShortDurationMs);
 }
 
+class ThreadWithSyntheticDelay : public SimpleThread {
+ public:
+  ThreadWithSyntheticDelay()
+      : SimpleThread("delay_test", SimpleThread::Options()) {}
+
+  virtual void Run() OVERRIDE {
+    TRACE_EVENT_SYNTHETIC_DELAY(kThreadedDelayName);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ThreadWithSyntheticDelay);
+};
+
+TEST_F(TraceEventSyntheticDelayTest, ThreadedSetup) {
+  // This test is designed to exercise various multithreaded scenarios with
+  // synthetic delays so that dynamic analyzers like TSAN can spot any

[Alexander Potapenko, 2014/07/15 14:30:15]

That's 'TSan', not 'TSAN' :)

Have you actually tried running it on this test?

+  // problems.
+  ThreadWithSyntheticDelay threads[2];
+
+  for (size_t i = 0; i < arraysize(threads); ++i)
+      threads[i].Start();

[Alexander Potapenko, 2014/07/15 14:30:15]

I think there should be two-space indentation here (and in the loop below)

+  TraceEventSyntheticDelay* delay =
+      TraceEventSyntheticDelay::Lookup(kThreadedDelayName);
+  delay->SetTargetDuration(
+      base::TimeDelta::FromMilliseconds(kShortDurationMs));
+  for (size_t i = 0; i < arraysize(threads); ++i)
+      threads[i].Join();
+}
+
 }  // namespace debug
 }  // namespace base