Revert "[vm] Don't enable the profiler by default. Enable the profiler at startup with --observe, o…

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index 12b31d01f1a32731b7b46d34203c4a52939f6afd..a99b48ee84b38090e31fdc1e74dc7b6e2eef88a3 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -78,7 +78,6 @@ void Profiler::InitOnce() {
   // Zero counters.
   memset(&counters_, 0, sizeof(counters_));
   NativeSymbolResolver::InitOnce();
-  ThreadInterrupter::InitOnce();
   ThreadInterrupter::SetInterruptPeriod(FLAG_profile_period);
   ThreadInterrupter::Startup();
   initialized_ = true;
@@ -98,13 +97,6 @@ void Profiler::Shutdown() {
   ASSERT(initialized_);
   ThreadInterrupter::Shutdown();
   NativeSymbolResolver::ShutdownOnce();
-#if defined(HOST_OS_LINUX) || defined(HOST_OS_MACOS) || defined(HOST_OS_ANDROID)
-  // TODO(30309): Free the sample buffer on platforms that use a signal-based
-  // thread interrupter.
-#else
-  delete sample_buffer_;
-  sample_buffer_ = NULL;
-#endif
 }
 
 void Profiler::SetSampleDepth(intptr_t depth) {