[chrome-remote-control] Use empty --inject_scripts instead of /dev/null.

This fixes windows where /dev/null doesn't exist. See:
http://build.chromium.org/p/chromium.perf/builders/Win7%20GPU%20%28ATI%29%20Perf/builds/6108/steps/robohornetpro/logs/stdio

BUG=None
TEST=Manual on linux and windows.
TBR=simonjam@chromium.org

Review URL: https://codereview.chromium.org/11362119

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166242 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed