Fix the ChromeVox generate_deps.py to create the parent dir for the output file.

BUG=417570
NOTREECHECKS=true
NOTRY=true
TBR=dmazzoni@chromium.org

Review URL: https://codereview.chromium.org/600333002

Cr-Commit-Position: refs/heads/master@{#296636}

chrome/browser/resources/chromeos/chromevox/tools/generate_deps.py

@@ -42,6 +42,11 @@ def main():
 
   path_rewriter = PathRewriter(options.prefix_map)
 
+  # Create the generated deps file's parent directory.
+  output_dir = os.path.dirname(os.path.abspath(options.output_file))
+  if not os.path.exists(output_dir):
+    os.makedirs(output_dir)
+
   # Write the generated deps file.
   with open(options.output_file, 'w') as output:
     for path in args: