Add annotated steps for dart_services

tools/utils.py

Index: tools/utils.py
diff --git a/tools/utils.py b/tools/utils.py
index 3c1eacb8fd4d7c6475b781538fdc0cbe8f0e4948..7da961cd2dd7fce1b63f36412135a83e42333ecc 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -272,6 +272,10 @@ def GetBuildRoot(host_os, mode=None, arch=None, target_os=None):
     build_root = os.path.join(build_root, GetBuildConf(mode, arch, target_os))
   return build_root
 
+def GetBuildSdkBin(host_os, mode=None, arch=None, target_os=None):
+  build_root = GetBuildRoot(host_os, mode, arch, target_os)
+  return os.path.join(build_root, 'dart-sdk', 'bin')
+
 def GetBaseDir():
   return BASE_DIR