Make stack sampling profiler sample beyond startup.

components/metrics/call_stack_profile_params.h

 // 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.
 
 #ifndef COMPONENTS_METRICS_CALL_STACK_PROFILE_PARAMS_H_
 #define COMPONENTS_METRICS_CALL_STACK_PROFILE_PARAMS_H_
 
+#include "base/time/time.h"
+
 namespace metrics {
 
 // Parameters to pass back to the metrics provider.
 struct CallStackProfileParams {
   // The process in which the collection occurred.
   enum Process {
     UNKNOWN_PROCESS,
     BROWSER_PROCESS,
     RENDERER_PROCESS,
     GPU_PROCESS,
@@ skipping 24 matching lines @@
     RENDER_THREAD,
     UTILITY_THREAD
   };
 
   // The event that triggered the profile collection.
   enum Trigger {
     UNKNOWN,
     PROCESS_STARTUP,
     JANKY_TASK,
     THREAD_HUNG,
-    TRIGGER_LAST = THREAD_HUNG
+    PERIODIC_COLLECTION,
+    TRIGGER_LAST = PERIODIC_COLLECTION
   };
 
   // Allows the caller to specify whether sample ordering is
   // important. MAY_SHUFFLE should always be used to enable better compression,
   // unless the use case needs order to be preserved for a specific reason.
   enum SampleOrderingSpec {
     // The provider may shuffle the sample order to improve compression.
     MAY_SHUFFLE,
     // The provider will not change the sample order.
     PRESERVE_ORDER
@@ skipping 10 matching lines @@
   Process process;
 
   // The collection thread.
   Thread thread;
 
   // The triggering event.
   Trigger trigger;
 
   // Whether to preserve sample ordering.
   SampleOrderingSpec ordering_spec;
+
+  // The time at which the CallStackProfileMetricsProvider became aware of the
+  // request for profiling. In particular, this is when callback was requested
+  // via CallStackProfileMetricsProvider::GetProfilerCallback(). Used to
+  // determine if collection was disabled during the collection of the profile.
+  base::TimeTicks start_timestamp;
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_CALL_STACK_PROFILE_PARAMS_H_