Allow configuring CPU profiler sampling interval using public API

src/cpu-profiler.cc

Index: src/cpu-profiler.cc
diff --git a/src/cpu-profiler.cc b/src/cpu-profiler.cc
index 34bebb8eca1bfe8cd220240ff297fa972d8430f4..35fe7888646c0e37adcc5944947d3f15feaeabf4 100644
--- a/src/cpu-profiler.cc
+++ b/src/cpu-profiler.cc
@@ -363,6 +363,8 @@ void CpuProfiler::SetterCallbackEvent(Name* name, Address entry_point) {
 
 CpuProfiler::CpuProfiler(Isolate* isolate)
     : isolate_(isolate),
+      sampling_interval_(TimeDelta::FromMicroseconds(
+          FLAG_cpu_profiler_sampling_interval)),
       profiles_(new CpuProfilesCollection()),
       next_profile_uid_(1),
       generator_(NULL),
@@ -376,6 +378,8 @@ CpuProfiler::CpuProfiler(Isolate* isolate,
                          ProfileGenerator* test_generator,
                          ProfilerEventsProcessor* test_processor)
     : isolate_(isolate),
+      sampling_interval_(TimeDelta::FromMicroseconds(
+          FLAG_cpu_profiler_sampling_interval)),
       profiles_(test_profiles),
       next_profile_uid_(1),
       generator_(test_generator),
@@ -390,6 +394,12 @@ CpuProfiler::~CpuProfiler() {
 }
 
 
+void CpuProfiler::set_sampling_interval(TimeDelta value) {
+  ASSERT(!is_profiling_);
+  sampling_interval_ = value;
+}
+
+
 void CpuProfiler::ResetProfiles() {
   delete profiles_;
   profiles_ = new CpuProfilesCollection();
@@ -418,8 +428,7 @@ void CpuProfiler::StartProcessorIfNotStarted() {
     generator_ = new ProfileGenerator(profiles_);
     Sampler* sampler = logger->sampler();
     processor_ = new ProfilerEventsProcessor(
-        generator_, sampler,
-        TimeDelta::FromMicroseconds(FLAG_cpu_profiler_sampling_interval));
+        generator_, sampler, sampling_interval_);
     is_profiling_ = true;
     // Enumerate stuff we already have in the heap.
     ASSERT(isolate_->heap()->HasBeenSetUp());