gn win: re-add event_recorder_stubs.cc, mistakenly removed before
gn win: re-add event_recorder_stubs.cc, mistakenly removed before

(This matches the gyp build)

R=brettw@chromium.org
TBR=brettw@chromium.org
BUG=354261

Review URL: https://codereview.chromium.org/467413002

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@289657 0039d316-1c4b-4281-b951-d872f2087c98

littlstar/chromium.src,ondra-novak/chromium.src,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,ondra-novak/chromium.src,littlstar/chromium.src,littlstar/chromium.src,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,ondra-novak/chromium.src,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,bright-sparks/chromium-spacewalk,ondra-novak/chromium.src,littlstar/chromium.src,ondra-novak/chromium.src,littlstar/chromium.src,littlstar/chromium.src,littlstar/chromium.src,littlstar/chromium.src,bright-sparks/chromium-spacewalk