Make stack sampling profiler sample beyond startup.

components/metrics/child_call_stack_profile_collector_unittest.cc

Index: components/metrics/child_call_stack_profile_collector_unittest.cc
diff --git a/components/metrics/child_call_stack_profile_collector_unittest.cc b/components/metrics/child_call_stack_profile_collector_unittest.cc
index 9a3a67af92d5be1ddd7012df5ab6f7a7a7c1c44a..a00336c20605b190b2be054efe29e5cd6c384d12 100644
--- a/components/metrics/child_call_stack_profile_collector_unittest.cc
+++ b/components/metrics/child_call_stack_profile_collector_unittest.cc
@@ -30,7 +30,7 @@ class ChildCallStackProfileCollectorTest : public testing::Test {
    public:
     using CallStackProfile = base::StackSamplingProfiler::CallStackProfile;
 
-    Receiver(mojom::CallStackProfileCollectorRequest request)
+    explicit Receiver(mojom::CallStackProfileCollectorRequest request)
         : binding_(this, std::move(request)) {}
     ~Receiver() override {}
 
@@ -73,6 +73,7 @@ class ChildCallStackProfileCollectorTest : public testing::Test {
   std::unique_ptr<Receiver> receiver_impl_;
   ChildCallStackProfileCollector child_collector_;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ChildCallStackProfileCollectorTest);
 };