new tool: download all GM images for a given builder, ready for skdiff
BUG=skia:1919
R=rmistry@google.com, bsalomon@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/143653006

git-svn-id: http://skia.googlecode.com/svn/trunk@13172 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/gm_json.py b/gm/gm_json.py
index 7cd4455..1aac663 100644
--- a/gm/gm_json.py
+++ b/gm/gm_json.py
@@ -104,6 +104,8 @@
   hash_digest: the hash digest of the image to retrieve
   gm_actuals_root_url: root url where actual images are stored
   """
+  # TODO(epoger): Maybe use url_or_path.join() so that, for testing, this can
+  # return either a URL or a local filepath?
   return '%s/%s/%s/%s.png' % (gm_actuals_root_url, hash_type, test_name,
                               hash_digest)