[heap] Add foreground/background UMA measurements for for main GC events.

Bug: chromium:814144
Change-Id: Idd729757608a714921254874af98a4a201340870
Reviewed-on: https://chromium-review.googlesource.com/981146Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52414}

src/counters.h

@@ -1148,10 +1148,20 @@ class RuntimeCallTimerScope {
 #define HISTOGRAM_TIMER_LIST(HT)                                               \
   /* Garbage collection timers. */                                             \
   HT(gc_compactor, V8.GCCompactor, 10000, MILLISECOND)                         \
+  HT(gc_compactor_background, V8.GCCompactorBackground, 10000, MILLISECOND)    \
+  HT(gc_compactor_foreground, V8.GCCompactorForeground, 10000, MILLISECOND)    \
   HT(gc_finalize, V8.GCFinalizeMC, 10000, MILLISECOND)                         \
+  HT(gc_finalize_background, V8.GCFinalizeMCBackground, 10000, MILLISECOND)    \
+  HT(gc_finalize_foreground, V8.GCFinalizeMCForeground, 10000, MILLISECOND)    \
   HT(gc_finalize_reduce_memory, V8.GCFinalizeMCReduceMemory, 10000,            \
      MILLISECOND)                                                              \
+  HT(gc_finalize_reduce_memory_background,                                     \
+     V8.GCFinalizeMCReduceMemoryBackground, 10000, MILLISECOND)                \
+  HT(gc_finalize_reduce_memory_foreground,                                     \
+     V8.GCFinalizeMCReduceMemoryForeground, 10000, MILLISECOND)                \
   HT(gc_scavenger, V8.GCScavenger, 10000, MILLISECOND)                         \
+  HT(gc_scavenger_background, V8.GCScavengerBackground, 10000, MILLISECOND)    \
+  HT(gc_scavenger_foreground, V8.GCScavengerForeground, 10000, MILLISECOND)    \
   HT(gc_context, V8.GCContext, 10000,                                          \
      MILLISECOND) /* GC context cleanup time */                                \
   HT(gc_idle_notification, V8.GCIdleNotification, 10000, MILLISECOND)          \

src/heap/heap.cc

@@ -1087,6 +1087,33 @@ void Heap::FinalizeIncrementalMarking(GarbageCollectionReason gc_reason) {
   }
 }
 
+HistogramTimer* Heap::GCTypePriorityTimer(GarbageCollector collector) {
+  if (IsYoungGenerationCollector(collector)) {
+    if (isolate_->IsIsolateInBackground()) {
+      return isolate_->counters()->gc_scavenger_background();
+    }
+    return isolate_->counters()->gc_scavenger_foreground();
+  } else {
+    if (!incremental_marking()->IsStopped()) {
+      if (ShouldReduceMemory()) {
+        if (isolate_->IsIsolateInBackground()) {
+          return isolate_->counters()->gc_finalize_reduce_memory_background();
+        }
+        return isolate_->counters()->gc_finalize_reduce_memory_foreground();
+      } else {
+        if (isolate_->IsIsolateInBackground()) {
+          return isolate_->counters()->gc_finalize_background();
+        }
+        return isolate_->counters()->gc_finalize_foreground();
+      }
+    } else {
+      if (isolate_->IsIsolateInBackground()) {
+        return isolate_->counters()->gc_compactor_background();
+      }
+      return isolate_->counters()->gc_compactor_foreground();
+    }
+  }
+}
 
 HistogramTimer* Heap::GCTypeTimer(GarbageCollector collector) {
   if (IsYoungGenerationCollector(collector)) {
@@ -1339,6 +1366,10 @@ bool Heap::CollectGarbage(AllocationSpace space,
       HistogramTimerScope histogram_timer_scope(gc_type_timer);
       TRACE_EVENT0("v8", gc_type_timer->name());
 
+      HistogramTimer* gc_type_priority_timer = GCTypePriorityTimer(collector);
+      HistogramTimerScope histogram_timer_priority_scope(
+          gc_type_priority_timer);
+
       next_gc_likely_to_collect_more =
           PerformGarbageCollection(collector, gc_callback_flags);
     }

src/heap/heap.h

@@ -1961,6 +1961,7 @@ class Heap {
   // - GCFinalizeMCReduceMemory: finalization of incremental full GC with
   // memory reduction
   HistogramTimer* GCTypeTimer(GarbageCollector collector);
+  HistogramTimer* GCTypePriorityTimer(GarbageCollector collector);
 
   // ===========================================================================
   // Pretenuring. ==============================================================