Support parallel captures from the StackSamplingProfiler.

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 662a285377ec593ebf1dd99d2826dc354551a295..fa842a94318ff79d8f1614969f065329cc50c7bf 100644
--- a/base/profiler/stack_sampling_profiler_unittest.cc
+++ b/base/profiler/stack_sampling_profiler_unittest.cc
@@ -882,11 +882,12 @@ TEST(StackSamplingProfilerTest, MAYBE_ConcurrentProfiling) {
   WithTargetThread([](PlatformThreadId target_thread_id) {
     SamplingParams params[2];
     params[0].initial_delay = TimeDelta::FromMilliseconds(10);
-    params[0].sampling_interval = TimeDelta::FromMilliseconds(0);
-    params[0].samples_per_burst = 1;
+    params[0].sampling_interval = TimeDelta::FromMilliseconds(1);
+    params[0].samples_per_burst = 10;
 
-    params[1].sampling_interval = TimeDelta::FromMilliseconds(0);
-    params[1].samples_per_burst = 1;
+    params[0].initial_delay = TimeDelta::FromMilliseconds(10);
+    params[1].sampling_interval = TimeDelta::FromMilliseconds(1);
+    params[1].samples_per_burst = 10;
 
     CallStackProfiles profiles[2];
     ScopedVector<WaitableEvent> sampling_completed;
@@ -911,14 +912,9 @@ TEST(StackSamplingProfilerTest, MAYBE_ConcurrentProfiling) {
     EXPECT_EQ(1u, profiles[completed_profiler].size());
 
     size_t other_profiler = 1 - completed_profiler;
-    // Give the other profiler a chance to run and observe that it hasn't.
-    EXPECT_FALSE(sampling_completed[other_profiler]->TimedWait(
-        TimeDelta::FromMilliseconds(25)));
-
-    // Start the other profiler again and it should run.
-    profiler[other_profiler]->Start();
-    sampling_completed[other_profiler]->Wait();
-    EXPECT_EQ(1u, profiles[other_profiler].size());
+    // Give the other profiler a chance to finish and verify it does no.
+    EXPECT_TRUE(sampling_completed[other_profiler]->TimedWait(
+        TimeDelta::FromMilliseconds(250)));
   });
 }