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

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index a99b48ee84b38090e31fdc1e74dc7b6e2eef88a3..8f5bd6e65d0a39868a2d118334613ccf345f782d 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -77,7 +77,7 @@ void Profiler::InitOnce() {
   Profiler::InitAllocationSampleBuffer();
   // Zero counters.
   memset(&counters_, 0, sizeof(counters_));
-  NativeSymbolResolver::InitOnce();
+  ThreadInterrupter::InitOnce();
   ThreadInterrupter::SetInterruptPeriod(FLAG_profile_period);
   ThreadInterrupter::Startup();
   initialized_ = true;
@@ -96,7 +96,6 @@ void Profiler::Shutdown() {
   }
   ASSERT(initialized_);
   ThreadInterrupter::Shutdown();
-  NativeSymbolResolver::ShutdownOnce();
 }
 
 void Profiler::SetSampleDepth(intptr_t depth) {