[chromedriver] Only delete temp files that start with "chromedriver_".

chrome/test/chromedriver/run_buildbot_steps.py

Index: chrome/test/chromedriver/run_buildbot_steps.py
diff --git a/chrome/test/chromedriver/run_buildbot_steps.py b/chrome/test/chromedriver/run_buildbot_steps.py
index 4c1cee2d69036873f92a3fa409bc4b941446983f..bf973fb019f64e8183db0f631be9f19edb240922 100755
--- a/chrome/test/chromedriver/run_buildbot_steps.py
+++ b/chrome/test/chromedriver/run_buildbot_steps.py
@@ -385,12 +385,13 @@ def _CleanTmpDir():
   print 'cleaning temp directory:', tmp_dir
   for file_name in os.listdir(tmp_dir):
     file_path = os.path.join(tmp_dir, file_name)
-    if os.path.isdir(file_path):
-      print 'deleting sub-directory', file_path
-      shutil.rmtree(file_path, True)
     if file_name.startswith('chromedriver_'):
-      print 'deleting file', file_path
-      os.remove(file_path)
+      if os.path.isdir(file_path):
+        print 'deleting sub-directory', file_path
+        shutil.rmtree(file_path, True)
+      else:
+        print 'deleting file', file_path
+        os.remove(file_path)
 
 
 def _GetCommitPositionFromGitHash(snapshot_hashcode):
@@ -497,6 +498,13 @@ def main():
 
   _CleanTmpDir()
 
+  # Make sure any subprocesses (i.e. chromedriver) create temp files under
+  # $TMPDIR/chromedriver_*, so that they can be cleaned up by _CleanTempDir().
+  if util.IsWindows():
+    os.environ['TMP'] = os.environ['TEMP'] = util.MakeTempDir()
+  else:
+    os.environ['TMPDIR'] = util.MakeTempDir()
+
   if not options.revision:
     commit_position = None
   else: