Add comment about updating webrtc.DEPS when rolling gflags

BUG=none
R=niklas.enbom@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2070004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4575 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/DEPS b/DEPS
index 8da3f9d..eccce43 100644
--- a/DEPS
+++ b/DEPS
@@ -42,6 +42,8 @@
   "third_party/expat":
     Var("chromium_trunk") + "/src/third_party/expat@" + Var("chromium_revision"),
 
+  # When rolling gflags, also update deps/third_party/webrtc/webrtc.DEPS/DEPS
+  # in Chromium's repo.
   "third_party/gflags/src":
     (Var("googlecode_url") % "gflags") + "/trunk/src@84",