Run optional GPU trybots against changes to media/audio/ .

media/gpu/PRESUBMIT.py

Index: media/gpu/PRESUBMIT.py
diff --git a/gpu/PRESUBMIT.py b/media/gpu/PRESUBMIT.py
similarity index 77%
copy from gpu/PRESUBMIT.py
copy to media/gpu/PRESUBMIT.py
index d993bd90a5c8ae70e0ee24a6c7e70215d2732239..48adb49834d01869855f461a534c54a381812b54 100644
--- a/gpu/PRESUBMIT.py
+++ b/media/gpu/PRESUBMIT.py
@@ -2,7 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Top-level presubmit script for gpu.
+"""Top-level presubmit script for media/gpu/.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
@@ -13,8 +13,11 @@ import re
 def PostUploadHook(cl, change, output_api):
   """git cl upload will call this hook after the issue is created/modified.
 
-  This hook adds extra try bots list to the CL description in order to run
-  Blink tests in addition to CQ try bots.
+  This hook modifies the CL description in order to run extra GPU
+  tests (in particular, the WebGL 2.0 conformance tests) in addition
+  to the regular CQ try bots. This test suite is too large to run
+  against all Chromium commits, but should be run against changes
+  likely to affect these tests.
   """
   rietveld_obj = cl.RpcServer()
   issue = cl.issue