overscroll: Add a browser-test for the aura implementation.

The test verifies that overscroll performs navigation correctly on
pages with and without touch event handlers.

BUG=160668
TBR=joi@chromium.org (for content_tests.gypi)

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=168547

Review URL: https://codereview.chromium.org/11414048

git-svn-id: http://src.chromium.org/svn/trunk/src/build@168600 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

filename_rules.gypi

@@ -78,6 +78,7 @@
     }],
     ['<(use_aura)==0 or >(nacl_untrusted_build)==1', {
       'sources/': [ ['exclude', '_aura(_unittest)?\\.(h|cc)$'],
+                    ['exclude', '_aura(_browsertest)?\\.(h|cc)$'],
                     ['exclude', '(^|/)aura/'],
       ]
     }],