[MemSheriff] Disable failing tests

BUG=395172
R=miu@chromium.org, thestig@chromium.org
TBR=miu@chromium.org, thestig@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/408483003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284133 0039d316-1c4b-4281-b951-d872f2087c98

tools/valgrind/gtest_exclude/content_browsertests.gtest-drmemory.txt

+# All WebRTCBrowserTests fail - see http://crbug.com/395172
+WebRtcBrowserTest.*