Introducing phased profiling framework

components/metrics/profiler/tracking_synchronizer.h

Index: components/metrics/profiler/tracking_synchronizer.h
diff --git a/components/metrics/profiler/tracking_synchronizer.h b/components/metrics/profiler/tracking_synchronizer.h
index fefe8d9457eb7c9e91798261f890cf3b7c9590d6..dfeb43f9a9b89d71a8d5fb6dfff84519baca3847 100644
--- a/components/metrics/profiler/tracking_synchronizer.h
+++ b/components/metrics/profiler/tracking_synchronizer.h
@@ -13,6 +13,8 @@
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
 #include "content/public/browser/profiler_subscriber.h"
 
 // This class maintains state that is used to upload profiler data from the
@@ -51,6 +53,11 @@ class TrackingSynchronizer
   static void FetchProfilerDataAsynchronously(
       const base::WeakPtr<TrackingSynchronizerObserver>& callback_object);
 
+  // Called when a profiling phase completes. |profiling_event| is the event
+  // associated with completing the phase and starting a new one.
+  static void OnProfilingPhaseCompletion(
+      ProfilerEventProto::ProfilerEvent profiling_event);
+
   // ------------------------------------------------------
   // ProfilerSubscriber methods for browser child processes
   // ------------------------------------------------------
@@ -84,6 +91,11 @@ class TrackingSynchronizer
   int RegisterAndNotifyAllProcesses(
       const base::WeakPtr<TrackingSynchronizerObserver>& callback_object);
 
+  // Notifies all processes of a completion profiling phase. |profiling_event|
+  // is the event that caused the phase change.
+  void NotifyAllProcessesOfProfilingPhaseCompletion(
+      ProfilerEventProto::ProfilerEvent profiling_event);
+
   // It finds the RequestContext for the given |sequence_number| and notifies
   // the RequestContext's |callback_object_| about the |value|. This is called
   // whenever we receive profiler data from processes. It also records that we
@@ -109,6 +121,19 @@ class TrackingSynchronizer
   // reuse for a long time).
   int last_used_sequence_number_;
 
+  // Sequence of events associated with already completed profiling phases. The
+  // index in the vector is the phase number. The current phase is not included.
+  std::vector<ProfilerEventProto::ProfilerEvent>
+      phase_completion_events_sequence_;
+
+  // Time of the profiling start. Used to calculate times of phase change
+  // moments relative to this value.
+  const base::TimeTicks start_time_;
+
+  // Times of starts of all profiling phases, including the current phase. The
+  // index in the vector is the phase number.
+  std::vector<base::TimeTicks> phase_start_times_;
+
   DISALLOW_COPY_AND_ASSIGN(TrackingSynchronizer);
 };