Add process lifetime annotations to stack samples.

components/metrics/call_stack_profile_metrics_provider.cc

Index: components/metrics/call_stack_profile_metrics_provider.cc
diff --git a/components/metrics/call_stack_profile_metrics_provider.cc b/components/metrics/call_stack_profile_metrics_provider.cc
index 9f323fdc28a48f2708826ddd768e1a8118dc8367..a4f64a79b3a5830d1c7874cdf1feba87c7af7e56 100644
--- a/components/metrics/call_stack_profile_metrics_provider.cc
+++ b/components/metrics/call_stack_profile_metrics_provider.cc
@@ -229,7 +229,7 @@ void CopySampleToProto(
     const StackSamplingProfiler::Sample& sample,
     const std::vector<StackSamplingProfiler::Module>& modules,
     CallStackProfile::Sample* proto_sample) {
-  for (const StackSamplingProfiler::Frame& frame : sample) {
+  for (const StackSamplingProfiler::Frame& frame : sample.frames) {
     CallStackProfile::Entry* entry = proto_sample->add_entry();
     // A frame may not have a valid module. If so, we can't compute the
     // instruction pointer offset, and we don't want to send bare pointers, so
@@ -256,11 +256,46 @@ void CopyProfileToProto(
   if (ordering_spec == CallStackProfileParams::PRESERVE_ORDER) {
     // Collapse only consecutive repeated samples together.
     CallStackProfile::Sample* current_sample_proto = nullptr;
+    uint32_t phases = 0;
+    uint32_t activities = 0;
     for (auto it = profile.samples.begin(); it != profile.samples.end(); ++it) {
       if (!current_sample_proto || *it != *(it - 1)) {
         current_sample_proto = proto_profile->add_sample();
         CopySampleToProto(*it, profile.modules, current_sample_proto);
         current_sample_proto->set_count(1);
+
+        // Phases are "set only" so current is always superset of last-seen.

[Mike Wittman, 2016/11/02 21:44:04]

Also, this logic could stand to be extracted into its own function.

[Mike Wittman, 2016/11/02 21:44:04]

The process phase/activities encoding should have tests.

[bcwhite, 2016/11/03 18:29:50]

OMG the existing tests are ugly!  <shudder>
Done.

[bcwhite, 2016/11/03 18:29:50]

Done.

+        uint32_t bits = it->process_phases & ~phases;
+        for (size_t bit = 0; bits != 0 && bit < sizeof(phases) * 8;
+             ++bit, bits >>= 1) {
+          if (bits & 1) {
+            current_sample_proto->add_process_phase(
+                static_cast<metrics::ProcessPhase>(1 << bit));
+          }
+        }
+
+        // New activities can begin.
+        bits = it->current_activities & ~activities;
+        for (size_t bit = 0; bits != 0 && bit < sizeof(phases) * 8;
+             ++bit, bits >>= 1) {
+          if (bits & 1) {
+            current_sample_proto->add_activities_begun(
+                static_cast<metrics::ProcessActivity>(1 << bit));
+          }
+        }
+
+        // And existing activities can end.
+        bits = activities & ~it->current_activities;
+        for (size_t bit = 0; bits != 0 && bit < sizeof(phases) * 8;
+             ++bit, bits >>= 1) {
+          if (bits & 1) {
+            current_sample_proto->add_activities_ended(
+                static_cast<metrics::ProcessActivity>(1 << bit));
+          }
+        }
+
+        phases = it->process_phases;
+        activities = it->current_activities;
       } else {
         current_sample_proto->set_count(current_sample_proto->count() + 1);
       }