Make stack sampling profiler sample beyond startup.

components/metrics/child_call_stack_profile_collector_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/metrics/child_call_stack_profile_collector.h"
 
 #include <memory>
 #include <utility>
 #include <vector>
 
@@ skipping 55 matching lines @@
   const std::vector<ChildCallStackProfileCollector::ProfilesState>&
   profiles() const {
     return child_collector_.profiles_;
   }
 
   base::MessageLoop loop_;
   mojom::CallStackProfileCollectorPtr receiver_;
   std::unique_ptr<Receiver> receiver_impl_;
   ChildCallStackProfileCollector child_collector_;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(ChildCallStackProfileCollectorTest);
 };
 
 // Test the behavior when an interface is provided.
 TEST_F(ChildCallStackProfileCollectorTest, InterfaceProvided) {
   EXPECT_EQ(0u, profiles().size());
 
   // Add profiles before providing the interface.
   CollectEmptyProfiles(
       CallStackProfileParams(CallStackProfileParams::BROWSER_PROCESS,
@@ skipping 82 matching lines @@
   CollectEmptyProfiles(
       CallStackProfileParams(CallStackProfileParams::GPU_PROCESS,
                              CallStackProfileParams::GPU_MAIN_THREAD,
                              CallStackProfileParams::THREAD_HUNG,
                              CallStackProfileParams::PRESERVE_ORDER),
       1);
   EXPECT_EQ(0u, profiles().size());
 }
 
 }  // namespace metrics