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;

[Mike Wittman, 2017/07/01 02:44:06]

Do we need to move this from a callback param to inside CallStackProfileParams
if we use the wrapper callback approach? I'm concerned that this makes it very
easy to miss the extra step required to set this value after construction,
whereas providing as a callback parameter is checked by the compiler.

 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_CALL_STACK_PROFILE_PARAMS_H_