Reduce CPU usage when no isolates need to be profiled.

runtime/bin/process.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/dartutils.h"
 #include "bin/io_buffer.h"
 #include "bin/platform.h"
 #include "bin/process.h"
 #include "bin/socket.h"
+#include "bin/utils.h"
 
 #include "include/dart_api.h"
 
 namespace dart {
 namespace bin {
 
 static const int kProcessIdNativeField = 0;
 
 int Process::global_exit_code_ = 0;
 dart::Mutex* Process::global_exit_code_mutex_ = new dart::Mutex();
@@ skipping 200 matching lines @@
   Process::SetGlobalExitCode(status);
 }
 
 
 void FUNCTION_NAME(Process_GetExitCode)(Dart_NativeArguments args) {
   Dart_SetReturnValue(args, Dart_NewInteger(Process::GlobalExitCode()));
 }
 
 
 void FUNCTION_NAME(Process_Sleep)(Dart_NativeArguments args) {
+  ScopedBlockingCall blocker;
   int64_t milliseconds = 0;
   // Ignore result if passing invalid argument and just set exit code to 0.
   DartUtils::GetInt64Value(Dart_GetNativeArgument(args, 0), &milliseconds);
   TimerUtils::Sleep(milliseconds);
 }
 
 
 void FUNCTION_NAME(Process_Pid)(Dart_NativeArguments args) {
   // Ignore result if passing invalid argument and just set exit code to 0.
   intptr_t pid = -1;
@@ skipping 62 matching lines @@
   int external_length = strlen(system_string);
   uint8_t* buffer = NULL;
   Dart_Handle external_array = IOBuffer::Allocate(external_length, &buffer);
   memmove(buffer, system_string, external_length);
   if (utf8 != system_string) free(const_cast<char*>(system_string));
   Dart_SetReturnValue(args, external_array);
 }
 
 }  // namespace bin
 }  // namespace dart