Introducing phased profiling framework

components/metrics/profiler/tracking_synchronizer_observer.h

Index: components/metrics/profiler/tracking_synchronizer_observer.h
diff --git a/components/metrics/profiler/tracking_synchronizer_observer.h b/components/metrics/profiler/tracking_synchronizer_observer.h
index b9301bb268e4d0c97319916752f2d31dd231834e..0e943508079bd814169fae18b759ff563f74c21f 100644
--- a/components/metrics/profiler/tracking_synchronizer_observer.h
+++ b/components/metrics/profiler/tracking_synchronizer_observer.h
@@ -5,21 +5,53 @@
 #ifndef COMPONENTS_METRICS_PROFILER_TRACKING_SYNCHRONIZER_OBSERVER_H_
 #define COMPONENTS_METRICS_PROFILER_TRACKING_SYNCHRONIZER_OBSERVER_H_
 
+#include <vector>
+
+#include "base/process/process_handle.h"
+#include "components/metrics/proto/chrome_user_metrics_extension.pb.h"
+#include "content/public/common/process_type.h"
+
+namespace base {
+class TimeDelta;
+}
+
 namespace tracked_objects {
-struct ProcessDataSnapshot;
+struct ProcessDataPhaseSnapshot;
 }
 
 namespace metrics {
 
+// Set of profiling events, in no guaranteed order. Implemented as a vector
+// because we don't need to have an efficient .find() on it, so vector<> is more
+// efficient.
+typedef std::vector<ProfilerEventProto::ProfilerEvent> ProfilerEvents;
+
 // Observer for notifications from the TrackingSynchronizer class.
 class TrackingSynchronizerObserver {
  public:
-  // Received |profiler_data| from a single process of |process_type|.
+  // TODO(vadimt): Consider isherman@ idea: I'd change the phase_start and
+  // phase_finish from TimeDeltas to TimeTicks.  And I'd omit the |past_events|
+  // list -- either in favor of a single ProfilerEvent that corresponds to the
+  // phase, or a method on the TrackingSynchronizer that can translate a
+  // profiling_phase to a ProfilerEvent.
+
+  // Received |process_data_phase| for profiling phase |profiling_phase| from a
+  // single process of |process_type|. The phase start and finish times,
+  // relative to the start time are |phase_start| and
+  // |phase_finish|. All profiling phases prior to the reported one have already
+  // completed, and each completion was associated with an instance of
+  // ProfilerEventProto::ProfilerEvent. |past_events| contains events associated
+  // with completions of phases prior to the reported one.
   // The observer should assume there might be more data coming until
-  // |FinishedReceivingData()| is called.
+  // FinishedReceivingData() is called.
   virtual void ReceivedProfilerData(
-      const tracked_objects::ProcessDataSnapshot& profiler_data,
-      int process_type) = 0;
+      const tracked_objects::ProcessDataPhaseSnapshot& process_data_phase,
+      base::ProcessId process_id,
+      content::ProcessType process_type,
+      int profiling_phase,
+      base::TimeDelta phase_start,
+      base::TimeDelta phase_finish,
+      const ProfilerEvents& past_events) = 0;
 
   // The observer should not expect any more calls to |ReceivedProfilerData()|
   // (without re-registering).  This is sent either when data from all processes