Make stack sampling profiler sample beyond startup.

components/metrics/call_stack_profile_metrics_provider.h

Index: components/metrics/call_stack_profile_metrics_provider.h
diff --git a/components/metrics/call_stack_profile_metrics_provider.h b/components/metrics/call_stack_profile_metrics_provider.h
index 5c4f0db7f94e39dd53dd15c84e35df876d8f2852..3412978dac914a28ff693cb3fafcf34dfd76aef7 100644
--- a/components/metrics/call_stack_profile_metrics_provider.h
+++ b/components/metrics/call_stack_profile_metrics_provider.h
@@ -7,6 +7,7 @@
 
 #include <vector>
 
+#include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/profiler/stack_sampling_profiler.h"
@@ -14,8 +15,17 @@
 #include "components/metrics/metrics_provider.h"
 
 namespace metrics {
+
 class ChromeUserMetricsExtension;
 
+// Internal to expose functions for testing.
+namespace internal {
+
+// Returns the process uptime as a TimeDelta.
+base::TimeDelta GetUptime();
+
+}  // namespace internal
+
 // Performs metrics logging for the stack sampling profiler.
 class CallStackProfileMetricsProvider : public MetricsProvider {
  public:
@@ -41,27 +51,33 @@ class CallStackProfileMetricsProvider : public MetricsProvider {
   // StackSamplingProfiler, and should not be reused between
   // StackSamplingProfilers. This function may be called on any thread.
   static base::StackSamplingProfiler::CompletedCallback GetProfilerCallback(

[Mike Wittman, 2017/07/13 18:10:29]

This can be made private or moved into the anonymous namespace in the .cc,
depending on test usage.

[Alexei Svitkine (slow), 2017/07/13 18:36:14]

Done. Moved to internal namespace, since it was used from test.

-      const CallStackProfileParams& params);
+      CallStackProfileParams* params);
+
+  // A version of GetProfilerCallback() that sets up parameters for browser
+  // process startup sampling. The callback should be immediately passed to the
+  // StackSamplingProfiler, and should not be reused.
+  static base::StackSamplingProfiler::CompletedCallback
+  GetProfilerCallbackForBrowserProcessStartup();
 
   // Provides completed stack profiles to the metrics provider. Intended for use
   // when receiving profiles over IPC. In-process StackSamplingProfiler users
   // should use GetProfilerCallback() instead. |profiles| is not const& because
   // it must be passed with std::move.
   static void ReceiveCompletedProfiles(
-      const CallStackProfileParams& params,
-      base::TimeTicks start_timestamp,
+      CallStackProfileParams* params,
       base::StackSamplingProfiler::CallStackProfiles profiles);
 
+  // Whether periodic sampling is enabled via a trial.
+  static bool IsPeriodicSamplingEnabled();
+
   // MetricsProvider:
   void OnRecordingEnabled() override;
   void OnRecordingDisabled() override;
   void ProvideGeneralMetrics(ChromeUserMetricsExtension* uma_proto) override;
 
  protected:
-  // Finch field trial and group for reporting profiles. Provided here for test
-  // use.
-  static const char kFieldTrialName[];
-  static const char kReportProfilesGroupName[];
+  // base::Feature for reporting profiles. Provided here for test use.
+  static const base::Feature kEnableReporting;
 
   // Reset the static state to the defaults after startup.
   static void ResetStaticStateForTesting();