Added histogram to track distribution of requested idle notifications.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index c53c9a75ec71ee5ae6ce36e8588c9e1a2b2c5dc4..d163900ec6ed9652c7c189e00c3d35bc3149adfb 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -53,17 +53,17 @@ Heap::Heap()
       amount_of_external_allocated_memory_at_last_global_gc_(0),
       isolate_(NULL),
       code_range_size_(0),
-// semispace_size_ should be a power of 2 and old_generation_size_ should be
-// a multiple of Page::kPageSize.
+      // semispace_size_ should be a power of 2 and old_generation_size_ should
+      // be a multiple of Page::kPageSize.
       reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
-      max_semi_space_size_(8 * (kPointerSize / 4)  * MB),
+      max_semi_space_size_(8 * (kPointerSize / 4) * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
       max_executable_size_(256ul * (kPointerSize / 4) * MB),
-// Variables set based on semispace_size_ and old_generation_size_ in
-// ConfigureHeap.
-// Will be 4 * reserved_semispace_size_ to ensure that young
-// generation can be aligned to its size.
+      // Variables set based on semispace_size_ and old_generation_size_ in
+      // ConfigureHeap.
+      // Will be 4 * reserved_semispace_size_ to ensure that young
+      // generation can be aligned to its size.
       maximum_committed_(0),
       survived_since_last_expansion_(0),
       sweep_generation_(0),
@@ -4268,6 +4268,7 @@ bool Heap::IdleNotification(int hint) {
   intptr_t step_size =
       size_factor * IncrementalMarking::kAllocatedThreshold;
 
+  isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(hint);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());