Make stack sampling profiler sample beyond startup.

components/metrics/public/interfaces/call_stack_profile_collector.mojom

 // 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.
 
 module metrics.mojom;
 
 import "mojo/common/file_path.mojom";
 import "mojo/common/time.mojom";
 
 // These structs mirror the corresponding types in base::StackSamplingProfiler.
@@ skipping 48 matching lines @@
 
   RENDER_THREAD,
   UTILITY_THREAD,
 };
 
 enum Trigger {
   UNKNOWN,
   PROCESS_STARTUP,
   JANKY_TASK,
   THREAD_HUNG,
+  PERIODIC_COLLECTION,
 };
 
 enum SampleOrderingSpec {
   MAY_SHUFFLE,
   PRESERVE_ORDER,
 };
 
 struct CallStackProfileParams {
   Process process;
   Thread thread;
   Trigger trigger;
   SampleOrderingSpec ordering_spec;
 };
 
 interface CallStackProfileCollector {
   Collect(CallStackProfileParams params,
           mojo.common.mojom.TimeTicks start_timestamp,
           array<CallStackProfile> profiles);
 };