Correct third_party/hwcplus/README.chromium src URL

In https://codereview.chromium.org/237633002, it was pointed out
that third_party/hwcplus/README.chromium should point to a
chromium.googlesource.com url but this url couldn't exist until
after landing 237633002. Correct the url now that it's possible.

BUG=361139
R=tfarina@chromium.org

Review URL: https://codereview.chromium.org/241333002

git-svn-id: http://src.chromium.org/svn/trunk/src/third_party/hwcplus@264703 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
diff --git a/README.chromium b/README.chromium
index 9735b0c..c4a19ed 100644
--- a/README.chromium
+++ b/README.chromium
@@ -1,6 +1,6 @@
 Name: Hardware Composer Plus
 Short hwcplus
-URL: http://src.chromium.org/viewvc/chrome/trunk/src/third_party/hwcplus/
+URL: https://chromium.googlesource.com/chromium/src/third_party/hwcplus/
 Version: 1.4
 License: Apache 2.0
 Security Critical: yes