Return start/end profiling time in microseconds instead of milliseconds

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 100ddc21b04df31d8a383d7502602868ae8237f6..c0f7a97f790a674dedff7013c5fa7bf5730a5be5 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -7591,15 +7591,15 @@ const CpuProfileNode* CpuProfile::GetSample(int index) const {
 }
 
 
-double CpuProfile::GetStartTime() const {
+int64_t CpuProfile::GetStartTime() const {
   const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
-  return profile->start_time_ms();
+  return profile->start_time_us();
 }
 
 
-double CpuProfile::GetEndTime() const {
+int64_t CpuProfile::GetEndTime() const {
   const i::CpuProfile* profile = reinterpret_cast<const i::CpuProfile*>(this);
-  return profile->end_time_ms();
+  return profile->end_time_us();
 }