Search for buildtools in the gclient root, if not in the main repo.

gclient_utils.py

Index: gclient_utils.py
diff --git a/gclient_utils.py b/gclient_utils.py
index a21e65a5fc31c5d01af67dc395f1ea65fabea86d..069d5d759e669317815ea069353e1b05358f2554 100644
--- a/gclient_utils.py
+++ b/gclient_utils.py
@@ -684,7 +684,11 @@ def GetBuildtoolsPath():
 
   # Some projects' top directory is not named 'src'.
   source_dir_name = GetGClientPrimarySolutionName(gclient_root) or 'src'
-  return os.path.join(gclient_root, source_dir_name, 'buildtools')
+  buildtools_path = os.path.join(gclient_root, source_dir_name, 'buildtools')
+  if not os.path.exists(buildtools_path):
+    # Buildtools may be in the gclient root.
+    buildtools_path = os.path.join(gclient_root, 'buildtools')
+  return buildtools_path
 
 
 def GetBuildtoolsPlatformBinaryPath():