Fix a minor regex bug.

Match against '.', rather than any character (how '.' is treated
in a regular expression).

Previous to this, xfermodes_8888*png matched the expression.

R=epoger@google.com

Review URL: https://codereview.chromium.org/26709003

git-svn-id: http://skia.googlecode.com/svn/trunk@11714 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/gm_json.py b/gm/gm_json.py
index c2a01f1..0620bca 100644
--- a/gm/gm_json.py
+++ b/gm/gm_json.py
@@ -83,7 +83,7 @@
 GM_ACTUALS_ROOT_GS_URL = 'gs://chromium-skia-gm/gm'
 
 # Pattern used to assemble each image's filename
-IMAGE_FILENAME_PATTERN = '(\S+)_(\S+).png'  # matches (testname, config)
+IMAGE_FILENAME_PATTERN = '(\S+)_(\S+)\.png'  # matches (testname, config)
 
 def CreateGmActualUrl(test_name, hash_type, hash_digest,
                       gm_actuals_root_url=GM_ACTUALS_ROOT_HTTP_URL):